So it's dawn, drizzling, and I'm in the middle of a state forest. It's so quiet I don't even see any deer! Then suddenly a stealth fixie is 5 feet behind me. Scared me out of my wits. He had come to the park too late last night and the gates were closed (they're never locked, but he didn't know that) and he had pulled his bike off the car and biked in--in complete darkness on curvy roads he didn't know with no light. That would have been an experience. Anyway, we did 3 miles until my chain fell off.

It was* fun talking and riding.

Then later I met a roadie coming from the other direction, and he stuck his arm straight out. I thought it was a wave, but then I thought it was a special hand signal telling me a car was behind me. Which one was it?

We use that as a signal for left turns around here. Since roadies neither signal or wave, he was probably just stretching.

When cycling thru a state forest just after dawn, that signal means "THERE IS A BEAR CHASING ME!"
Otherwise it probably just means "Ride closer to the shoulder, you're taking up the whole road..."