I don't think this is a change with AA. IIRC, they never allowed you to book via the web less than 2 hours out. Calling reservations or in person at the counter was the only way to do last-minute tickets. Now it seems that the first method is unreliable. If this is important to you, I'd contact PAR/D and complain--last minute tickets make a lot of money and if enough people complain to justify the cost, they could at least add more help to the EXP line to service ticketing calls.