The exact same thing happened to me, I thought someone had keyed my back fender, and almost had a heart attack until I realized it was just crud that had stuck to the adhesive that was left behind from the sticker. The dealership just didn't go a very good job with the initial detail.

download the BRZ shop manual here.

the Pre-Delivery Inspection is covered from pages 55-72. every new owner should do their own PDI just in case. if there are any problems, it's better to know them sooner than later.

That's what these are! I read a while back about it, but I couldn't find it in the search, so I just waited until someones else found it haha. I'll pop them in when I do my exhaust

Anyone still have the clear plastic protection stuck to the plastic edge of the side panel trim where you enter into the back seat?

I just noticed and removed them a few days ago... Nobody can fit into the backseats, so I didn't even see them until we flipped the seat forward to put a bag back there. :)

...Paul