I haven't made the change. Are you serious?
Now that I think of it, if it is a ticket exchange, you might be right. That explains why, for example, when I recently changed tickets for my folks (EY J, AA redemption before 22 March but changed after 22 March, free change according to rules), they got issued new e-ticket numbers, but I didn't check the issue date.
That said, just because the issue date has changed doesn't necessarily mean it has 1 year validity. AA could be well in their rights to issue an e-ticket with a shorter validity, viz. matching the date on the base e-ticket (which is kept in record against the PNR).