Ardern showed she wasn't one to miss an opportunity, telling the host, an avid Lord of the Rings fan, that they wanted to make him a citizen of Hobbiton near to where she'd grown up. He could catch a direct flight from Chicago, she told him.
Colbert reminded her she was in New York but she told him direct flights were starting from Chicago next month, Air New Zealand would have been happy.
It was a relief that Colbert didn't, unlike other interviews here, dwell on the young leader who gave birth in office. He did mention it in passing though, but being vehemently anti-Donald Trump, he had to gauge The Prime Minister's view of the man.
But she shrewdly wasn't walking into that trap, deftly avoiding whether she was laughing at, or along with, the President as he claimed to be one of the best ever American leaders when he addressed the UN.
Backstage Ardern got to rub shoulders with American acting royalty: the veteran Candice Bergen, who kicked off the show and who herself walked into the Trump bait, admitting as an 18-year-old dating him - he sounded like something straight out of Anchorman, a burgundy symphony she recalled, although she couldn't recall how the date was set up, probably a phone call from him, she mused.
Around the same time she dated former American Secretary of State Henry Kissinger and to the obvious delight of Colbert admitted he was the better date.
So Ardern had a formidable act to follow and was flatteringly given the same screen time.
In reality, though it was more of a Trump show, with filming of it delayed because he was giving his fourth press conference of his presidency, talking about today's hearing of his Supreme Court nominee Brett Kavanaugh and the allegations of his high school sexual escapades.
For the audience in this Democrat city, the delay was worth it, particularly when Trump referred to things in the past involving President George Washington.
So Ardern may not have been the star of the show, but even if those sitting around me in the audience admitted to never having heard of her, they liked what they heard and that in this so-called dirty old town is high praise indeed.