Join Date: Oct 2006
Location: London, UK
Programs: BA Gold, VS Silver, SQ Silver, IHG Plat Amb, Hilton Gold, Marriott Plat, Accor Silver, Radisson Prem
Posts: 16,880
I've had similar 'operational' changes in the past, including one notable one where I was moved from 1K to 1A with no explanation (not that it really mattered), without there being any passenger in 1K! 1K was fully operational as a passenger moved forward after takeoff.
In summary, I don't think even BA know sometimes why their systems change seats.