First off, I know that this is how LCD screens work, but I have never seen such a visible grid on my 2010 MBA 13". This grid is especially visible in the dark grey areas (e.g. The part where the tabs are in Safari) and when you hover with your eyes over it. I can see this effect on 2 2011 MBA 13" with a LG screen. Unfortunately I have no Samsung to test it, but I know my 2010 MBA did not have this problem.