Do you mean Main Cabin Extra? That doesn't expedite your TSA screening anyway. It just gets you Group 5 boarding, but since you're Gold you'll get group 4. You also would have had free MCE seat selection at 24 hours prior to flight, if available. Also - recommend you call and ask them to drop and re-add your AA number if you booked your trip *BEFORE* you became Gold. If you booked after, then your status should properly reflect.
And you don't have to get to the airport 2 hours before you normally would have. Maybe 30 minutes. Stop at the check in counters and they'll probably be able to fix it quick.
Just FYI, Main Plus is a “bundled” fare offering by AA in a number of markets.