Here's 2 bikes taken from the same angle which you can see by looking at the surface of the seat.
Dee Tee's :-
Mine :-
The front edge of my back panel looks lower, but I cannot find any adjustment anywhere.
Sorry about all this lads, but I've got more chance of getting answers here than trying my luck at the local BMW dealer, mainly because my French is crap.
Maybe the seat itself is a little wonky. Complain about it next service. That just doesn't look ok. I have some gap there too, but yours is much worse.
Maybe its a problem with the way the tail piece was formed? Im not plastics expert, but maybe for some reason in got destorted after it came out of the mold?
I would say the only way to figure this out is to try another seat on your bike... if you can find one. If that doesnt solve it then ordering a new tail trim piece might be in order. Just my .02