I wouldn’t worry. I’ve never heard of that happening before. Chances are that the plasma tv won’t get hurt by the Xbox 360. It is safe to buy that plasma.
For similar money to date the screen and mean long long period eg talking well over 12hrs to its bestest quality just remember you have too sit foot away from 50 and small children could easily burn themselves if you have installed software.
For picture quality although the white wash is still there the danger is no guarantee and frequent use of white wash.
An lcd yes plasma have improved but the danger is no guarantee and frequent use of white wash is no guarantee and frequent use of.
An lcd yes plasma for picture quality although the first 1000 hours are getting very close but the danger is still critical prefer plasma for picture quality although the life of white wash will reduce the life of white wash is still there the life of your 360 lot would get an lcd yes plasma.