I just stumbled across this thread ... maybe I can help to solve a bit of the mystery around this coin.
The WoG Series 4 will be presented at an event in May (GCZPQG) and I believe that there will be a special edition of about 150 coins that will be given away as prices for a cache-competition. As far as I know, all these coins will have a special mission.
The one you've found seems to be the only activated one and is dropped in the event listing.
I believe that after the event the regular edition will be sold via geocachingshop.de as the previous edition of this coin.
Hope to help,
Dirk
(an upper 'Z' of Team 'zZZz')