Thanks for the tip about calling web services rather than the EXP desk. My knee-jerk reaction is to call the EXP desk for everything
so it's good to know when I should look elsewhere for help.
I did email web services, and here is the reply I received:
Your fare was and is indeed guaranteed for 24 hours I regret the
confusion. I believe the problem may have had to do with the fact that
you are on the west coast and because you were purchasing close to
midnight. This error has been reported however, should you ever
encounter this again please don't hesitate to contact our AA.com Web
Services by telephone for immediate assistance.
They also credited my account for the 1,000 miles.
But this just confuses things more. 1) They think it had to do with the fact I was on the west coast, but the web page specifically said it was on hold until 11:59 PM
PDT -- so was that wrong? 2) They said that my fare is guaranteed for 24 hours. As others have pointed out in this thread, I had put the reservation on hold more than 24 hours before I went to actually book it.
So are fares actually guaranteed for 24 hours, or until 11:59 PM on the day after you place the reservation on hold? I'm still not sure... I'll email for clarification again.
I'm satisfied with the outcome in this case, I just want to learn the rules so I don't have problems with this in the future.