Hey!
First off I'm still relatively new to this. My second time posting on here so I hope I'm doing things right.
I recently purchased this 2013 UNC. Proof like set. Noticed there is a small mark on the reverse face? I'm no expert but this is the first I have seen of this in a proof like set.
Wondering what you all think.? Is this an actual error? And is this common?
You will see the spot on right side of the coin

