The top of my 920's screen gets too hot as well during charging or extended use or when the ambient temperature is hot. But I haven't eroded the screen matrix as the above pic yet. Will be a bit cautious from now on not to let the phone heat up beyond a threshold.
I use this app called wiper ... I think it was made specifically for the 925 I run it on the hour cycle grey option when I go to bed and the app bar burn in is gone in the morning.