During the cocktail hour, a woman approached me to ask if I would take a family portrait at some point in the evening. She introduced herself, and after I told her my name, she had this "I think I know you look" cross her face. At that instant I recognized her as well and we gave each other a big hug.
It turns out that I knew the family of the bride! They had been friends of my family back in Toronto, but we lost touch over time and hadn't seen each other in over 30 years. I actually attended the wedding of the father of the bride back in the late 70s (thus explaining why his wife looked familiar to me). It turned out that there was a seat free at the table of this family, so they invited me to sit with them for dinner and we had a chance to get caught up. It was quite a surreal experience.