I have a 2012 13" Macbook Pro. A few weeks ago I left the laptop open in front of a window and when I started using it again there's a noticeable milky spot in the middle of the screen. It isn't visible when the computer is off, but when the screen is on the spot is visible, especially on a black background. Not too sure what to do, if any one has any ideas as to what the spot may be or how I can fix it it would be greatly appreciated!