I haven't seen this happen before- this is a 777-300ER with Prem Plus seating (sold as Y). I was in seat 20B, and about 2-3 days ago got an email that, due to an aircraft change, I had been moved to row 46! What's strange is that the seat map still shows the original aircraft- but with rows 20,21,22 completely empty, although I cannot change my seat to any seat in the (seemingly empty) Prem Plus rows. The flight is only slightly over 24 hours away- doesn't it seem like they'd have the aircraft assigned at this point? And if this is the aircraft, why did they empty out the Premium Plus cabin?