Imac 20" Screen


I just bought a refurbished wonderful 20" iMac from Apple. It's the first flat monitor I've ever had. I've noticed that when I fill the screen with solid black, it's not completely uniform -- there are areas that are slightly less black.

I doubt this is crucial to my work, but I wanted to see this if this is something that get worse later on. (Maybe I should just get the extended warranty and answer my own question!)

Thanks for any advice you can give.