I agree that they may have made some sort of change.

Last week I tried repeatedly to check in on-line for a simple MCI-ORD trip and kept getting messages that I didn't have an e-ticket and would have to check in at the airport. I knew darn well I had an e-ticket but called our corporate travel agent who said yes, I did have an e-ticket and suggested I call AA. It turned out that the little "schedule change" AA had made, which included a new flight number, was enough to confuse the system. When the right person punched the right buttons in AA's system, I was able to print my boarding pass.