2009 Cervelo P2 v. P2C

Hi,

I'm looking at purchasing my first tri bike and was wondering if anyone knows why some of the Cervelo P2's from 2009 say "P2C" in big letters on the seat stay and others just say "P2"?  I was thinking that the "C" means for carbon, but I'm looking at a carbon one that just says "P2".  Any help would be greatly appreciated.

-JB