I was recently asked for my AAA card for the first time ever. It was rather odd.
To add, this appears only on their regular website and mobile website. This is not yet present on their mobile app (iPhone, at least). Also, I can confirm that one of my old expired AAA numbers works fine, so it looks like they’re validating structure/format rather than the status of the membership. This doesn’t mean they won’t audit the numbers in the future with AAA, of course.
Based on some testing, it looks like it will take 429 + valid Club Code (CDP) + 10 digit number. CDP #’s can be found on sites like Hertz and other websites (if only a two digit code, add a 0; not sure about those that are more than 3 digits). Also tested with a CAA number and it is fine.