I have the same problem, but only when the set has been turned on for a while (I guess it has to warm up) for the problem to show up.
Manufactured September 2006
Made in Mexico
Below is an image. Note, the first image below appears worse in the pic then it actually is in person. The picture was taken this way to illustrate what the clouds looks like during a dark scene.
Updated: Below pics were taken in the dark on 12/09/06 during the Space...