This is a normal thing. I mentioned earlier in thread that perhaps the LEDs are purposely placed away from the corners to prevent light bleed and that sort of thing. Just a theory of mine though never bothered looking it up or asking any manufacturer. It’s hardly noticeable unless you’re looking for it or you have an all white screen.I've noticed that too and it vanishes if you move your viewing position to be in front of a corner. i.e. it's a viewing angle issue. It also vanishes on all 4 corners if you back up far enough...again decreases viewing angle to the corners.