I lightened up the image and there is a part of the coin that is delaminating. It is hard to determine if this is a result of a problem with the planchet as the coin was minted...or if it is a result of corrosion that occurred later in the coins life.
The color indicates that some corrosion has taken a toll on the coin.
I wouldn't rule out a lamination error but I wouldn't rule it in entirely either.
Thanks,
Bill