It is a small indention for a sticker that came on the old Stillen spoilers. It is too small for any factory stickers that I have seen and I've opted out in putting just some crap sticker there. I'll worry about it when the 280 is done. In the meantime my facia and interior are my bigger issues for the vert.
Here is the same spoiler when it was on my cherry red, can see the area better.