Her 85-year-old grandfather was in Waikato Hospital, which is full to bursting. And so at 11.30 on Tuesday night the hospital attempted to discharge him.
It's not the fault of the staff, said Ardern - nor is this issue about her - but it's indicative of the state of our health system. It's not fit for purpose.
Health Minister Jonathan Coleman, predictably, turned on Ardern.
He said it was "edgy" for Ardern to politicise her grandfather's situation. And that, in one sentence, showed the remarkable arrogance of the man.
This is why Coleman is accused by some within the sector of being incredibly disconnected from the health system. He's the king of spin, and as he showed here, he's an expert at playing the man, and not the ball.
Address the issue, Minister Coleman. Our health system is under enormous strain.
On Tuesday, Waikato Hospital was forced to put a message up on Facebook saying all elective surgery had been cancelled. The whole lot.
They were overloaded. They could only deal with emergencies, they said. And even then, you should expect to wait.
And what did Coleman say? This floored me, actually. He said: "The key thing is, the hospital is able to cope." Cope with what exactly, Minister?
He should pay a visit to Waikato Hospital. Go and talk to the fraught staff there, go and see those overflowing wards, and the challenges those incredibly hard-working staff are facing.
And it's the same across the country. Find me a DHB that says they don't have funding issues. Find me a DHB that says they're not under-staffed or over-worked. And there is no risk to the health of the public because they're meeting every patient's needs. You won't find one. Not one.
And you've got to look at why our health system is buckling under the strain.
Look at what they're dealing with. Record high immigration, the obesity epidemic and all the health challenges that brings, child poverty and the record number of infants and children being admitted to our hospitals, and an ageing population.
There are so many reasons there is such a huge demand on our hospitals. And those hospitals are not funded to meet the needs of the public.
That Coleman can stare down a TV camera and say "the key thing is the hospital is coping" shows just how removed he is from the coalface of our health system.
Overnight, a lot of people have contacted us with some pretty distressing stories about what they've endured in our health system.
I won't go into them here, but another story broke overnight of a baby dying at Waikato Hospital because the mother was bumped from her elective caesarean at least once, because an emergency C-section took priority.
Doctors at Waikato had warned managers that elective caesareans were competing with acute C-sections for the only dedicated theatre, and it was a life-threatening situation.
Then the unthinkable happened. A baby died.
I read that story in the Herald this morning. It's traumatic. My heart goes out to those parents. I can't begin to imagine what it would be like to lose your child. I truly can't imagine that.
But at the same time, it makes me angry too.
Angry that as a first-world country we're finding ourselves in this situation. Healthy babies shouldn't die because their mothers are bumped from theatre. That should never happen. Never.
This is about people. Not politics. Address the issue, Minister. This is on your watch.
Again, I come back to Jonathan Coleman's quote. "The key thing is the hospital can cope."
No it can't, Minister. It really can't. And what are you doing about that?