I have an AA-ticketed reservation which has changed from a 3 hour layover to a 13.5 hour layover as a result of an AS flight number change. There's no schedule change, but the flight from STS to LAX changed designation from AS 7465to AS 3466. AA says that AS 3466 is not available for them to book, so they bumped us to a much much earlier flight.

Does anybody know why AA can book some AS flights and not others? Is there any significance to the change in flight number from 7465 to 3466?