Mine built in July 2012 is flat black. See my sig. Me thinks they ran out of black ones just like they ran out of the 307 style wheels.
Edit: just saw you linked to my post. Hehe, I'm stupid.
And yes, all the 4 cylinder x3 I saw on the line that day had black grilles...even the many European diesel ones I saw. Wife made fun of me because was looking at this carefully...nerd.