Aha--I've solved the mystery on AA.com!!! Since we're getting sort of long in the tooth, I always say 2 Seniors in the place where it asks for # of passengers. When I designate the passengers as "seniors", the fare is $149. When I change the designation to "adults", the fare is $449. So the secret fare pipeline is thinking of yourself as a senior. Who knew!! Anyway, I didn't think American or any other airline had senior fares anymore, but I guess they do, or it's a software glitch--one or the other. Anyway, in the future, I'll check the fares for both adults and seniors --you never know, it may be the other way for some destinations.