Help! How to deal with random run in...

Today was the weirdest day.

I ran into the N's dad this morning walking to a friend's house. He was always lovely to me and acted as a sort of career mentor. I haven't seen him in many months so I felt nervous when I saw him, but I knew he would be kind. We spoke briefly, and as anticipated, he was warm and kind.

Then this evening I was on a date and we go to a small restaurant and the N is there with his new wife and part of her family. I panicked as I tried to decide whether or not to try to leave. Had I been alone, I would have just turned on my heel back out the door, but I didn't know how to do that in such a way that wouldn't make my date exceedingly uncomfortable. The N is moving to NY with his new wife, so I was shocked to see that he was even in town. We didn't speak, but eventually he did see me and acknowledged me with a head nod, which I returned.

I proceeded to sit down with my date and I tried to be as pleasant as possible. I did fill him in on the fact that a guy I had been involved with previously was present, in case he noticed a change in my demeanor. He had noticed and was incredibly understanding and sensitive towards me. I have to acknowledge how nice it was to be sitting next to a guy who definitely cares about my feelings and feels concerned when I'm upset. Nevertheless, I can't help but replay my reaction and consider how the N might have interpreted the way I acted. Could he tell how nervous I was? Did he think I looked good? Did he expect me to say something? Etc. None of it really matters, and I wish I didn't care, but I do. I hope I handled it right.

Anyone else had a similar experience?