Can you provide a link to a snapshot? Sometimes the LCD panel looks like that if the right light hits it at a certain angle due to the way they are constructed.
My Pro2052 looks that way if you look close and down at the bottom of the display. When I did the tap on the scanner I discovered that there is a small thin gasket around the display, made of a type of foam and that was what I was seeing. I rearanged it a bit and that fixed it.
Does it look like a light spot - oval shaped? If so, it's the light diffuser not aligned properly. I've fixed one of those already. Others say it needs 'cleaned', but it's not a dirt issue - it's an alignment issue. The diffuser is not seated properly.