If they are the ones that made the mistake, why not?

Fortunately for us, they do allow mistakes to be corrected within 24 hours of ticketing. Yes, it is my responsibility to confirm the reservation when the email arrives or online. But, I should not have to make the agent repeat everything that she just did and whats to guarantee there has not been a reading mistake.

Of course, AA is not responsible for what the OP did with Marriott or anything unrelated after the phone call.