I've had 2 EF change of aircraft emails in the last 24 hours notifying me of a swap from 788 to 789 for BA31/BA32 in January. I immediately logged on to check my seats and realised that nothing has changed. According to BA seatmap it's always been a 789, I know this because I've selected 13K in J, and have seat alerts set up for 7A/K. If it was originally a 788, 13K would put me in WT+.
Is EF notifying me of a change that happened before I booked the flight in April, or is something else going on?