My 12" MacBook has this issue to a small degree. I have cut a piece of felt the size the laptop to put under the machine which completely solves the problem. Not elegant but effective.
Are you serious?
How old is it?
I would absolutely blow a gasket at Apple if my very expensive new notebook wasn't sitting flush on surfaces.
What's the point of all these fancy/expensive processes and materials they are using if they can't even beat out plastic at simply "being flat".