On the way to work I was merging onto the freeway and decided to get on it. Only through 2nd and 3rd. I let off at the top of third and let the engine coast down.. I gave it some more gas to pass traffic around 4000RPMs when the car bucked for a split second and I saw the SES light come on. It started flashing and I let off and put it in neutral immediately. It probably stayed on for about 20 seconds or so and then went away. The car doesn't smoke and still runs and idles fine. Anyone have any idea what it might be?