I was cruising home today, in 3rd, car under no real load. All of a sudden, what I can only describe as the car 'feeling like it hit something', the engine management light comes on for a brief moment, then it goes off and the car is fine. Any ideas what this was? Was it a misfire?

It was quite disturbing, I thought the brakes had come on some how, that's how jarring it was, but then it went straight back to normal.