Likely it was just the settings on the camera; someone likely changed something in the menu before you looked at it. The d600 should be just as capable as any high end camera at rendering color well. There are differences between Canon and Nikon color reproduction, but I'd have no objections to working with either, they are both good - just a little different. It's also possible that the Nikon screen was a little "green", it was a problem in the D4, but I don't know if it's a problem in the D600. Either way, the images aren't effected by the screen color - it was just annoying to some D4 users.
Will Canon drop it's prices before Christmas, well no one can be sure. My bet is no since we are still in the initial sock phase where the camera is in short supply in some parts of the world - they likely won't drop prices until they have extra stock. However I could be wrong, the Nikon deal is going to put pressure on them.