Wrong term, that's called Image persistence, that's quite rare, I have only heard about this once, few days ago, all I can tell you is making your screen go totally white or switch off for an hour or two (display a blank white image or off) and see if stuff goes away, LCDs experience backlight bleeding (happens to any LCD) or edge light dispersion
Image persistence, or image retention, is the LCD and plasma display equivalent of screen burn. Unlike screen burn, the effects are usually temporary and often times not visible without close inspection. Plasma displays experiencing severe image persistence can result in screen burn-in instead.
