There has been some threads regarding the color shift issue.
I was one of them that had the problem.
I didn't go through the Apple support,
but was concerned with LED Cinema Display overheating.
When used for many hours, the bottom left corner around the speakers was getting too hot.
Since the color shift problem came when it got hot,
I lowered the brightness setting.
Since the display comes in 100% brightness, I lowered it to about 90%.
Then the issue was gone.
The display wasn't overheating and the color shift issue no longer appeared.