I had the exact same thing happen on Monday night. the trans went into limp mode after the engine rpm fluctuated wildly between 1000 and 4000 all by itself, the trans failsafe warning cmae on. I parked the car for a few minutes, shut it off. When I restarted the warning cleared and the car ran fine. I have put about 200 miles on it since that episode. The local dealer says sometimes the computers give false or spuradic readings. It could be a sign of a lot of things from wire shorting to the beginning of a major trans failure. I'm gona run til it won't.

Ghost