One of the kids has a 2000 Grand Prix that does that all time. My husband will be driving it and the service engine soon light comes on. Then the next day, I'll drive it and it's not on anymore. It seems to be a random thing and I'm not really worried about it with that car. I guess I just figure that if the warning light goes out, whatever it was is ok now. Hopefully yours will stay off, but if it's on again and it bothers you, you might take it to the dealer right away and maybe they can see what the computer says.