Well, it could also be because a few month ago they had all of these great deals on the 7 series (I recall they had a $10k off promotion) and those cars have finally arrived (after assembly and the time it took to get them state side via the LONG boat ride)...
So now you are seeing more of them on the road. Honestly, I am glad there are a few more around. That means you won't be the only guy with a 7 series so the dealership should actually know how to work on one rather then experimenting with yours