Brought my display in to the Apple Store, the Genius assured me, that the grey band at the bottom of the screen is quite common among large LCD displays and that all iMac's have a slight grey bar on the edges of the screen, which varies in degree. He told me that is just how the display sits in front of the led's emitting the light.
Most people do not notice it, but I have OCD and well....yea.
I told him that I barely notice it, the screen is totally uniform, with no dead pixels and since it is a normal occurrence on large displays, just varies in degree, the chance that I may get a worse display is 50/50.
The tech also informed me that my display was one of the best he had scene, being uniform, no dead pixels, no yellowing and a normal grey bottom edge, at a very unnoticeable degree.
What really put my mind at ease, was the fact that all iMac's have it, it is normal for the LED backlight behind a 27" display. Obviously in varying degrees.
I am glad I went, I am happy to know my iMac checked out with flying colors, now I can finally enjoy my iMac.
Thanks, Apple.
P.S And for those who told me not to replace my display.....sorry I doubted you!
Thats all I needed to