MacBook screen dithering issue

Here are photos of my screen dithering issue on my new MacBook 2.4 GHz. Most MacBooks in the store (same model) had it, but some didn't.

Gradients and solid colours on websites show banding and dithering. The dithering is very visible with greys, gradients, and transparencies/shadows. The level of transparency is more pronounced than it is supposed to be. Images underneath the transparent sections are sharp, not blurry.