Hi how are you doing...
Are you sure it was an AA 777?
I don't think so. You must have confused with a 767. I know AA doesn't have the 777 yet.
2 distinctive features to recognize a 777 over a 767:
6-wheel landing gears
I'm sure that what you saw was a 767.
American flies them a lot out of O'Hare.
Does that clarify what you saw?