I recently picked-up an FN complete A2 upper from the EE.  However, when I got it, it was grey, not black.  Is this the correct color?  Thanks!

Sort of. Most issued weapons I have used have been the "Colt Grey". Most civilian sale rifles and parts are "black".

My FN is gray too.

If it bothers you, try spraying it with some Rem-Oil with Teflon. I have a PWA lower that when dry, would look grayish.. almost white. Multiple coatings of CLP did nothing. After a few days, the CLP would evaporate and it would go back to a gray-whitish color. Based on some advice here, I cleaned it using non-chlorinated brake cleaner and then sprayed with a heavy coat of Rem-Oil and then let it sit over night. Next day I wiped it down and did it again. I ended up with a nice even black color that lasts. My PWA lower was supposed to be black HCA so your results may vary if it is a gray HCA?