Australian quick Mitchell Starc petulantly hurled a ball at New Zealand's Mark Craig, when the batsman was proving obstinate on the final morning. Smith's reaction was swift.
He wasn't impressed and would be giving Starc a dressing down, he said publicly after the game.
"I was pretty disappointed with Starc's actions. I had a chat with him and he responded really well," Smith reiterated a couple of days later.
The first thing to note was there was no attempt to bury details of what Smith thought behind a veil of silence. He wasn't happy and he was out in front of the issue.
Not every Australian captain of recent times would have taken the same course of action. Allan Border, Australian batting great and the original Captain Grumpy, said he'd have preferred Smith to have kept his dressing down behind closed doors, but Border had no issue with Smith wearing his emotions on his sleeve on the field.
"I think he's [that] quirky kind of character - [where he is] emotional," said Border.
Think of Australian captains of modern times and an image forms. Typically unshaven, relentlessly chewing gum and with the narrow, flinty eyes of an old west gunslinger. Ian Chappell, Border, Mark Taylor, Steve Waugh, Ricky Ponting - tough guys who took no prisoners.
There are early signs Smith, for all his different physical appearance, may join them in his approach. Forget the youthful appearance; the kid plays for keeps.
The young man from Sydney set his sights on a cricket career early.
He had a touch of the cocky about him. As a schoolboy he quickly become used to being sledged by grizzled veterans in grade cricket.
One day, after a lengthy, persistent spray, he said to a fielder: "Mate, how old are you?"
"30".
"And you're still in second grade?" Touche.
He'd made his New South Wales debut at 19, not long after an incident which illustrates a relentless, determination towards the game which is intact today. Smith's school team were preparing to face local rivals, who featured a feared fast bowler.
The opening batsmen went missing. No one could be found to go in first.
So Smith donned the pads, corralled someone into opening with him and, as they set off for the middle, Smith turned and fixed his teammates a withering gaze and said "You guys need to harden the f*** up".
When he left school, Smith's eyes were firmly on making it in cricket.
He spent time in Kent as a 17-year-old, learning cricket and life. He was eligible to play for England due to his mother's heritage, but it was always the baggy green for the kid who obsessed about the game from a very young age.
Smith's first taste of test cricket didn't last long. He was sent back to state cricket to tighten a technique which was all over the place. Second time around, there was no going back.
So what of Smith the batsman?
The former No8 sits No2 in the world test rankings, among the elite, who also number New Zealand's champion Kane Williamson, England's Joe Root, Indian Virat Kohli, Warner and South Africans AB de Villiers and Hashim Amla. Take out the South Africans, who are over 30, and the next decade is set to be dominated by a scintillating Big Five.
All Smith's 11 test hundreds have been scored in the first innings, when teams are setting out their stall and looking to take charge.
In his career first innings (before yesterday) Smith averages 71.75. He's hit seven hundreds in his past 12 first innings, going back to last December, when he took four in successive tests against India, while filling in for an injured Michael Clarke as skipper.
He's a fidgeter at the crease, once counted to make 23 tugs, flicks, pulls, pushes and adjustments between two balls in an ODI last season.
He has developed a distinctive shot to leave the ball outside his off stump, an around and downward chopping movement past his legs, akin to swatting flies.
Don't be fooled. When the ball is on it's way, Smith is quick-footed and decisive in his shot selection. It's a distinctive method.
"I've listened to all the commentary around Steve's method and I think a lot of it is just noise," former batting great, and supreme classicist, Greg Chappell said.
"Steve is a bit of a nervy character so he's all got all these mannerisms, but that's all they are - just mannerisms. They're not impacting on what he's doing.
"I can tell you what good batsmen are, they're good thinkers, they have very good self-belief, they have a determination to be successful and they make good decisions.
"They manage their thought processes really well under pressure and that's probably more critical than the physical attributes."
Waugh says while Smith is not a technically perfect player "he has got that inner desire more to score runs, a bit like a [Sachin] Tendulkar. Once he gets a hundred, he wants to go on and get a big score every time."
Smith the captain will develop with time and, unless he turns out to be a dud, it'll be a while before Australia are looking for their next leader.
In the Australian side, only Josh Hazlewood (24), Starc (25), and Mitchell Marsh (24), are younger than the skipper.
The heart is on the sleeve in the field. Players are left in no doubt if he's unhappy.
"[If the] field's not quite right you can see him blowing up a bit," selector and former test batsman Mark Waugh said.
Betraying emotions isn't for everyone, but it's Smith's way.
"I don't think I'm that grumpy," he said. "I'm just really enjoying everything at the moment. I guess [making a statement] is pretty important. If it's needed [I'll do that]."
He's excited by the challenge of leading his country, and will do it on his terms.
As he should.
Steve Smith
Age: 26
Born: Sydney
Test debut: Against Pakistan, Lord's 2010
Tests: 35
Runs: 3144 at 55.15 (before yesterday)
Centuries: 11 (all in first innings')
