A Moment I Will Remember Forever

I don't know if there's a word for this kind of thing, but there have been a few mundane moments in my life when I thought, "I'm going to remember this forever, but I don't know why." The latest one happened yesterday on the blue line: someone had dropped their glasses on the ground. It was bothering me a lot, that the glasses were there, eventually to be crushed underfoot, so I bent over and picked them up and offered them to the lady sitting next to me. She declined. I put the glasses on the bench in between us. A few stations later, I got up and got off the train.