I am travelling on a DONE4 and have a BA segment DXB-LHR on a 747 in six weeks.
I booked this flight back in August and from FT advice I had 14A preallocated. (My preference is for downstairs).
Last Friday I was checking my booking and noticed that
CheckMyTrip was showing 13A

.
After gathering my thoughts and doing a closer inspection; 14A was still free. However 14B was now allocated where previously it had not been.
Using MMB, I set about reselecting 14A but changed my mind halfway through and chose 14K instead.
Does anyone have any experience of this type of thing happening? Or suggestions why?