I have a 24" Aluminum iMac, just bought a few weeks ago. I'm wondering if this issue is normal because of the glass screen, or if this shouldnt be happening. When the screen is dark (like in the flurry screen saver) the two bottom corners look brighter. This is not noticeable most of the time, but I did notice it when I tried to play Myst V which is a darker colored game. So, I'm wondering if this is normal or not.