This happened just this morning on my commute. Fellow lady cyclist got onto the highway a bit ahead of me, so I picked up the pace to catch up and say hi. She got into her rhythm and pulled ahead, I pedaled faster, and long story short, I ended up sprinting for a half-mile or so before catching up, hollering a cheerful 'Good morning!', realizing she had earbuds in, and dropping back. I didn't realize I could even go that fast! I hit 18 mph in an area where I usually top out at 13.
Funny thing is, the same thing happened a year or so ago, except I never caught up, not even when we hit town; I just wanted to thank her for the workout. I seem to be built (mentally) like a greyhound, always chasing that toy rabbit, just not very fast. Too bad there aren't more early commuters.