I can almost promise that it's the traction control. Mine does the same thing as well. And I can also tell when it's about to do this. Mine does exactly as described above. I run mine on the track and it DOES NOT DO IT on the track ever. Only on the street. Mine does this 100% of the time when the Traction Control IS ON. Only sometomes when it's off. Given that the TC is never 100% off, I think this is doing it. I noticed that when at the track, if the wheels start spinning after launch, the TC still activates when it's "off".

My belief is this is a function of the stability control. Thinking about it logically, the car doesn't have a Limited Slip Rear End. So, if you are already traveling at a good rate of speed and it senses the wheels begining to break lose, it comes on line to keep the car from losing stability. Without a LSD, if one side spins and one side hooks at 45 MPH, it could EASILY send the car into a skid/spin. I even think I remember seeing the TC light flash when this happens, but I can't say for sure, because I'm looking at the road.