Is the white gradient on ins creed a glitch or a feature for Xbox 360?

It looks like they made a sunset thing but failed at it! And its very annoying it makes like 1/4 of the screen look brighter every where and its a the top. I don't have a HD TV though and i don't plan to buy one. when you look at Ezio from the top (like rotating the camera) it all looks a little brighter. And normal when you look up at Ezio from the ground. Is this a feature of some sort or a bug?