So far, even if the screen was changed two times in the month I buyed my 47PFL6877H in july 2012, I was pretty satisfied with this TV.

But since a few days (of course I am no longer under warranty), the screen showed signs of light leaks at the bottom's corners, as shown in the picture I take (sorry for the focus) :

What can this be, given that the screen has never moved from its wall support for 2 years. And when this phenomenon appeared he disappeared after an hour and the screen was quite uniform in dark/grey, but now these leaks are visible all the time.

If someone has an idea, thank you in advance.