I recently pointed out a college crush (accompanied by her hubby and new kid) to the gf at a party. It's not like I'm still trying to hook up with her a decade later. The fact that the gf understands this speaks to why she's the gf. We're all adults here, let's recognize the past is the past, and the now is the now.
Different situation: what do you do when you run into someone you used to see or work with all the time, but you haven't seen him in a while. You remember their name clearly and greet them, then talk a little bit, and it becomes clear that they don't remember your name? This could be avoided by greeting them with something like, "Hey, Tom! John Smith, from K-State...how's it going?" But some folks fall in a gray area, where you don't want to insult them by offering your name as if you assume they wouldn't remember. Last time this happened to me, I concluded afterwards that I should have given the guy one of my cards with the "call me up and let's get lunch sometime," or something similar, as we wrapped things up.
if i wanted to talk to tom in my post-college life, then i would be talking to tom in my post-college life. if i see someone from ksu and i currently don't talk to them, then more than likely i will just ignore them and pretend like i didn't see them
