I have recently acquired a used Nikon D3000 and I've noticed its lcd has dark corners. Seems to have a spotlight in the center of the lcd though it's not affecting the actual image when opened in laptop. I just want to know what's causing this as this might be an issue that can affect other parts of the unit in the future. I've aso looked around the settings for possible configuration but can't find any and also can't find a related thread over the internet.
Please see pic below.