That is called a lamination error. It has peeled off on that area. Not a premium for this coin. If it were a BU coin, then there might be interest in it. But they are common to find. (and in most cases it is a distract from the coin and not a plus) The desired ones are BU showing an attached peel or huge peel.
http://goccf.com/t/357186
A little more information here.
http://goccf.com/t/357186
A little more information here.
























