Notify your dealer that there is an SIB for the center channel B&O speaker.
Here it is:
http://f10.m5post.com/forums/attachm...5&d=1385460069
Maybe there's another SIB for side speaker but I am not confident on that.
You sure it's the rear door speaker and not the B pillar? There's a B pillar rattle issue.. loose washer.
If it is the side speaker, and there's no SIB, they will probably replace it under warranty.