The PM was in the middle of a Facebook Live, talking to her nation about fuel prices. But viewers had their eye on something else.
The new mum sparked engagement murmurs when people noticed she was donning a large silver ring with a black stone on that finger.
NZ Herald reported that the ring may have in fact been on her right hand, and simply appears to be her left due to the phone's camera.
Ardern has shut down wedding talks in the past - when people confused the reasoning why her ring was on her wedding finger.
"I'm happy to confirm that I have eczema on my left hand, which causes me to rotate where I wear my beautiful onyx ring. So no, I am not engaged," Ms Ardern said at the time.
"I do however suffer from a small skin condition, which is not very romantic. Glad to have cleared that up."
The couple have been together since 2012, and are the parents to their daughter Neve.