No idea but you may be able to look up any new ticket in your online account to verify the number. Just a guess on my part, but if just a schedule change was involved and a new ticket was not issued, the number would likely stay the same.

I just went into my Delta account and under "Account Activity", I could find my past tickets and the corresponding numbers. Not sure if AA has this feature or not. I am going to try and find it.

AA appears to have the same feature. Log into your account and it is under "Activity" and does show the ticket number. You should be able to verify this way.