AA will guarantee the fare for 24 hours only. So if the off chance should there be a fare increase between now and 23 hours later, AA will honor the fare without a reprice. But if you decide to issue later.. say a week later, then your TA would have to reprice the same reservation irrespective if you have made changes or not. It's just the rules.

Any airline will always add the phrase, "Not guaranteed until ticketed". And that's exactly what it means.