Do you carry your MacBook Pro around a lot or place items on top of it, such as books and stacks of papers. The light faded areas that I see on most Macs are results of pressure applied on the back of the display during transport or just placing things on top of it. I used to use a 17" MacBook Pro in schol and I would place textbooks on it which caused it to develop a bright spot that kept getting bigger from the centre of the screen. You can also get it from some bags, or just about anything that applies pressure. Another way this can occur is with heat. Do you place your computer under a hot area or set hot drinks/plates on it (seems kind of strange but people have done it before). Those are the main causes that I have found of faded LCDs and bright spots. It cant really be undone if this is the case, but it can be stopped.
Hope this Helps