Moderator, Iberia Airlines, Airport Lounges, and Ambassador, British Airways Executive Club
Join Date: Feb 2010
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Posts: 63,804
I've had it occasionally, just update until you get the tick sign on MMB. It used to be particularly prevalent on mixed AA and BA bookings since (e.g.) middle names would get doubled or even tripled up.
The scan of bookings by the DHS is constant after 72 hours so the sooner the better, but you can just do it at the airport an hour from departure.
I wouldn't worry about it.