My 70" 632U had some green clouding in the middle of the screen on dark or black scenes. What I did was turn the TV off, then wipe the entire screen inside to out with a microfiber cloth applying very light pressure, similar to what you did. The green clouding completely disappeared. I got the idea from someone here on the forum with a similar problem. Mine has been fine ever since. So if it went away I wouldn't worry about it.