No light bleed from mine. Correction: I just looked again more closely, and I can see light where the center hinge attaches to the back. There's a small gap that allows light from the screen to leak through. I don't think it's anything to be concerned about.
A couple of weeks ago I was looking at the same thing. Strange design choice but in the end it doesn't matter to me. It may simply be MS's hardware inexperience showing (not having enough experience to consider such details).