I don't know. I didn't know at the time, nor do I know now.
As I rode the bus home from work the other day, I saw a woman get on the bus and I thought I saw something drop out of her bag on the ground just before she boarded. By the time I managed to get a look, she was on board and I would have had to speak immediately to tell her in time for it to be recovered. But it was a pack of cigarettes. So I said nothing because I was uncertain if I ought to speak and tell her and my uncertainty decided for me. Should I have told her that she lost her cigarettes?