My USPS Informed Delivery email for today says that I'm receiving a letter with a return address for Amtrak Guest Rewards, PO Box 2656, Omaha NE. That seems to be an address used by
First National Bank of Omaha.
Annoyingly, I just noticed that my Bank of America AF posted on 7/30 and so can't be refunded. Guess I'll try to maximize September spend.