It looks like one of two things: 1) damage to the airtite or 2) some foreign object trapped inside the airtite. It's not on the coin, itself, because you can see the reeds apart from it. Open the airtite and see if you can remove it. Chris
I got it open but the set is encased in a vacuum pack. Hard to tell if it's on the plastic. Probably is but cant feel anything.