Have a flight booked on AA, MCI-ORD-OMA (and return), next week. Had to book through aa.com since US' website couldn't find anything into OMA, entered my US FF# (and it seems to recognize my status, since it let me choose MCE for free and told me my checked bags would be free).
Then this morning, got an email from AA titled "We look forward to seeing you soon" and saying:
Join now and earn 1,638 miles for this trip
We are looking forward to your upcoming travel. We noticed that there was not an AAdvantageŽ number in your reservation. It's free and easy to enroll, and you'll become a member instantly!
Anyone else had this happen when flying AA with US #?