check engine light on 2004 360 coupe

My check engine light came on,but I just had it serviced 150 miles ago.I drove the car away from a stop light rather jerky and jumpy(on the damn cell phone).I don't know if that did it.I had the check engine light on prior to service (I suspect I didn't screw the gas cap on right) but the service cleared it last time.The car has 2000 miles thus far.Any input other than get off the phone and drive right?Thanks.