oion,
This is what Microsoft reaps by overpricing their product as a "premium" device. Defects like this are NOT premium and MS resisting warranty coverage because the defect is "cosmetic" wont help. Arrogance, like Apple's, is acceptable to an extent when they can back it up, but MS hasn't earned that yet in the hardware space and they will get slammed for it.
Regardless, to the OP, you just bought it, why is warranty coverage necessary? Just exchange it.
Man, I don't know what to tell people, or jinx myself, but mine is really flat and good.