This was something that put me off the Aura a little when I was trying to decide between it and the Paperwhite a while back. I knew there might be some shadow from the lights, but I could see a dark band along the top in both the display models I got to see in person and I knew it'd really bug me!
Having the dark band along both the top and bottom in yours seems a little more of an issue though, so I'd agree with the others about returning it. It does seem to be a flaw, but it does vary and if you return it you could be hopeful of getting a replacement model where the dark band is less noticeable.
However, if it doesn't really bother you and returns are a hassle.... then that's your choice. As long as you are happy enough reading on it, that's good enough for you so why worry. Happy reading.
