I'm late to the party here. Looking at the reverse, the horizontal lines in the shield and the inner left wing feathers (our visual right) seem a bit weak, and could possibly show signs of buffing. The eagle's right wing and the olive branch have different reflectivity than other central devices. Just a question, but could PCGS have seen something in these elements suggesting to them that someone tried to enhance the central design contrast with the fields, in an attempt to pass it as a CAM?
I'm not sure I would agree with that assessment, but I wonder if that is what PCGS thought.