I have heard of it. Check your cruise control and see if it was centered on the stalk.
I read somewhere where sometimes an electrical glitch can cause this to happen as they are drive by wire.
Someone wrote that they were at a stop sign and the car started through just like it had a mind of it's own (A4 auto). He set the brake, and it kept going. He put it in neutral and the engine reved to the limiter and shut itself down. Th dealer could not figure out the cause. One of the electrical wizards on another board said it could have been the cruise control controls. I keep mine in the Off position unless I'm using it.