I don't think anyone is trying to criticise you here. I understand what anvilheadII means and Yes it is just one word, but it's an important one. It sort of takes the sting out of it all.
If it were me, I think I'd smile a bit too and I know exactly what you mean. I think the majority of us would. There's nothing wrong with trying to see something positively especially with your calm reaction. There's something that gives you a bit of inner peace when there's an affirmation of someone acknowledging you positively, especially if it's someone who's hurt you. Are you making too much out of it? Possibly. Does it provide a bit of closure for you regardless? Definitely.
I think everyone needs to remember that we are all at different stages of recovery and coming to terms with things. Detachment isn't about forgetting, and detachment isn't about shutting down emotion toward somebody. It's accepting something for what it is, and going back to having a life. If and when you're ready to totally let go, then blocking him might be a good start. Your choice though. Your own pace for your own peace.