I am not sure if my experience is was related to being an AA PLT or having a B class ticket for my recent flight from MEX to ORD.
Checked in and received boarding pass showing seat 27A.
When I walked down the gangway to the plane the GA came running after me and asked me if I was willing to change my seat, after I told her that I wouldn't mind she handed me my new boarding pass, showing seat 1D.
I also saw them deboarding a family of four, who then came back on board later, but I don't know if that had anything to do with it.