Not right, but seems to be somewhat common. There is another thread here where several people have posted similar pictures, most a little worse than yours.
In fact, mine has this problem. Much worse than yours, I have about a 4.5 inch area centered below the front camera. It can only be seen when looking from a really low angle, just as in your photo. So in normal usage, it is not visible and doesn't seem to cause any kind of uneven lighting or anything.
I am debating whether to drive 40 miles to exchange it. It definitely "isn't right", but neither is it causing me any problem and my display is otherwise perfect (even lighting, no dust, no stuck pixels, etc). I would hate to exchange it and then find a defect in the next one that DOES bother me, so I still haven't decided whether to exchange it, or just keep it.