Take your car to a National franchised auto parts store and ask them to read the codes. It may not show anything, but it is free. The check engine light went out because you had completed enough drive cycles ( on/off start/stop) without an active fault then the light cleared itself. It has nothing to do with an oil change. You still may be holding a pending code, or it could be stashed away inside the ECU, BAS or some other module. If the shop you take your car to for the oil change can read DRB III codes and they aren't going to charge you an excessive $$$. Let them see what they can find, but without the DRB III you are wasting your money. Get the code number or numbers ( be specific write the number down do not just let them explain to you what the code means, you paid for it; GET THE NUMBER) and, so long as your car is running well just drive away, leave, don't let them talk you into some expensive repair unless you explicitly trust the people at that shop. Come back here and post the code if the shop can find one. There are a lot of smart people here who can give you good information, and then you can decide what action to take.

PS If there is any doubt as to the oil level use the dip stick and check it.