Lately on my LG I've been noticing lines appearing on the screen during scenes with a light background and in some cases you can make out a grid effect very faintly. Worst was Ice Age which shown this up a bit more than usual. Is this a normal thing with plasma's? Most of the time the picture is spot on, it is only very occasionaly that this happens and like I said it's when a very bright background comes on. I'd appreciate any thoughts on this. Thanks.