It could well be overheating. That could cause issues and if that is the case I would get it fixed before it does serious damage to other components.
It could also be a loose connection. The cable that connects the display to the motherboard could be loose and cause the screen to flicker when moved. The cable could also be damaged, leading to the same problem.
There is also the possibility that the display is going, or the graphics card/GPU is.
If the device is under warranty, I would contact the manufacturer.