I have a Blue from American Express from around the late 90's. I closed it a few years later but it's still showing up in my credit report. If I apply for and get approved for a new Blue from Amex, and ask them to backdate it, would it show up as if I have had the card the whole time on my credit report?
If so, that would bump up my AAoA a little.
Backdating isn't something requested, it just happens with how the AmEx system reports to the credit bureaus.