N told me once... quoting someone I can't remember... that you know it's true love when that other person is the only one you can imagine running into anytime, anyplace, in any mood or state of dress, and be genuinely happy to see them.
My mother says one of the things she likes about living in a small town is that she usually knows someone on the plane when she takes a flight, and that she sees someone she knows at the grocery store most times.
I, on the other hand, skulk off if I see someone I know in the grocery store and part of the whole thrill of air travel is that no one I know is aware of my precise location while I'm moving along.
All this said... I was driving across Portland the other evening, and stuck in traffic, in another car, across from me, in the lane facing the other way, was John! And to my friend N - yep, I just lit up, and forgot stress from work, the destination I was dreading, and my melted makeup. I was so happy and surprised to see him, and to exchange a grin and an air kiss across the evening maze of commuters.