Hmm, I too have gotten frequent notification that my Thanksgiving trip's schedule has changed. Once was a departure time change of < 5 min. Once was an aircraft change (from RJ to A319), once was with no apparent change at all. To add to my confusion, we are booked on two separate PNRs (for upgrade purposes, of course) and we do not get notifications at the same time for the same changes (it may be 24-48+ hrs between our notifications).