I was discussing programming puzzles with a new group of colleagues. The way these discussions typically go is that after most of us solve it, they will start giving hints/spoilers to others to keep the conversation flowing.

So I did this as usual and offered a hint to the last person (who was a woman) to not see the trick this time. It surprised me when she looked visibly upset and asked me why I was explaining it to her. I'm guessing this is because of her own insecurities that she was worried that I thought she was too dumb to solve it on her own otherwise. Up until this point her gender was irrelevant to me. I only explain stuff because the value of discussing interview problems is to get practice solving and explaining stuff to each other. But now I have to question whether I was "mansplaining" or not.

This minor event bothered me so much I never talked to her about programming puzzles ever again.