Depends in part what your fare class is, and how flexible your ticket is. As well as how much advanced notice you've had of the change.
But common courtesy would suggest calling AA and making a legitimate change, even if a fee is required. Otherwise, having missed your flight on a discounted ticket could render it valueless. Thought it is unlikely AA will take such a position, it is by twisting the rules over the years that the airlines have gotten themselves into the financial mess they found themselves in, even before the events of Sept. 11th. If you buy a full fare ticket, you buy flexibility for last minute changes. You pay for that privilege. If you buy a discounted ticket, you get specific times and dates for your flight, and you save accordingly. So I would have no concern if a change fee were charged on a discounted ticket, should it become necessary to take an earier flight. Some discount fares permit standby on earlier flights for no charge, others do not.
I think the airlines have become too lenient about some of these things, and end up subsidizing your company for the privilege of changes you employer should otherwise be paying for.