I was lucky enough to have scored an upgrade on an upcoming flight at the 3 day window; however, when I went to change my seat, the new system wouldn't let me. I got the following error message:

One or more of your requested seats are no longer available and could not be assigned. Please review your current seats and reselect if desired.
Message#SEA1032

Has anybody else run into this? I've sent an e-mail to Delta, but have not heard back.