I wonder. Do you see this noise in all plasma screens(at close range)?
All plasmas have a dithering noise, attributed to their operational principles. It is visible in some flat color areas, not all, but normally only at close range(I'd say about 4'-5'). At 7' and greater, I think it should not be discretely visible, unless you are looking for it and have the visual acuity of an Airforce pilot!
But if you see a noise all over the picture, and visible from 7', like a fuzzy analog broadcast, perhaps you should consider returning the unit for an exchange.
-Chris