I don't know if this is your issue, but I have an itinerary booked with AA in September. Every other day one of the flights moves by a tiny amount of time (e.g. 5 minutes) and some friendly robot sends me a very dense email about it where I have to go through manually and find out what it is (in this instance I think it's Amex GBT); sometimes the next email a day later is moving it back. You presumably did not use Amex GBT, but it does seem AA likes regularly retiming flights by a matter of minutes, which might be generating your message.