My Toshiba L455-S5009 laptop is only three months old and already it had developed a yellowish orange cloud over much of the display. This type of display uses led's to illiuminate each pixel, so there is no need for a lamp. I was told by a repair service in Mexico that the display needed to be replaced. Later that day I saw an identical Laptop at WalMart. Guess what? STAY AWAY FROM TOSHIBA LAPTOPS!
Have you tried to update the graphics driver? Perhaps that has something to do with it. If that doesn't work, it does indeed sound like the display is faulty. If the laptop is only 3 months old, contact Toshiba and they should replace it free of charge, as most laptops come with a one year warranty on them.