happened to me in september, doing the RDU-JFK-SFO. Same crew, same plane, same seat on my RDU-JFK flight as was on my Positioning flight JFK-RDU.

Since its a small plane, only one crew, but she smiled, and said "that was a quick turn around", i replied "it was cheaper for me to fly to RDU to take a dump and shower, than it was for me to have a plumber come fix my bathroom at New York rates." it was hilarious. But then i told her what the real reason was, and i was surprised that i was the first Milage runner she had seen or met. anyways, its cool.