So, I figured I'd come here and post my results on similar lights coming on.
I too, had this happen to me after a drive back from Stockton. Light turned on, engine started running like it was a gear lower than it actually was, throttle was reduced to either zero or FLAT OUT WOOOOOOOOOO, and my mileage was shot.
I freaked out, pulled over, and checked as many things as I could without taking apart the engine. (Learned my lesson: I'm keeping my bluetooth OBDII reader in my glove box from here on out.) Couldn't figure out what was wrong, so I limped the last 20 miles home, and got the reader, and the P0019 code.
Called up the dealer, they said to bring it in, as there was a technical service bulletin. Did so, and they reflashed my ECU, fortunately it took the first time and didn't require replacement. Went and had dinner, took a walk, and came back and drove home, with everything fine. Apparantly the problem was a corrupted "page" in the ECU.