I've encountered other cachers in NYC, here in PA, and several other states. The funniest was in Central Park where we waited for a guy to finish fishing and then we started to look after he walked away. He watched briefly and then came over and his first words were: "I'm not a muggle."
In my experience, everyone tends to introduce themselves right away and we have a great chat / search, though I have seen a few who were too shy or maybe didn't realize I was part of the inner circle of loons with a GPS.
Sometimes, I do feel like I'm
being watched - not necessarily by cachers. Certain types of caches just lend themselves to that...