No acceleration, "Service Transmission" C30 T5
 

Just bought a C30 T5 R with 140k. No problems the first couple of days. Then, I was taking off from a full stop at at a traffic light, barely took off as I pressed the pedal to the floor. Transmission Service Required or something like that came on. The RPMs did not climb like a slipping transmission. They appeared to be limited. Rolled up to next turnoff and parked for 5-10 mins. Restarted car, no warning message, and drive normal.

Any ideas where to start first? Thanks!