Pogo will be temporarily turning off Guest Passes on September 20th.
They had this to say about it :
We are making this adjustment for the short term as we work on some backend data migration. Once the update has been completed we will share that information with you and keep you up to date on when the guest passes return.
Squid's translation: Somehow, people have managed to abuse the guest pass system and have caused us to lose money. We are revamping the pass system to ensure that doesn't happen again.
That sounds about right!