Found this on another site but it still doesn't explain why we were not warned nor why the rarity was set so high.
Eric Musco went on the forums to explain the early embargo for the Star Cluster Nightlife Pack and the lack of reputation track for this shipment.
WTH Embargoing the Star Cluster pack in 2.8.1??? | 06.20.2014, 03:20 PM
Good question, let me explain a bit about this shipment of packs and how it works. The first thing that many of you noticed is that this shipment does not have a reputation track, this is intentional. The Star Cluster pack and the Club Vertica pack are a smaller, special shipment which is intended to run during Nar Shaddaa Nightlife Event.
What you will see is that Star Cluster will become embargoed on the launch of 2.8.1, which will also mark the launch of Club Vertica. Similarly, Club Vertica will only be available up to, or before, the launch of 2.9. I don’t have an exact date on when Club Vertica will be embargoed but I will let you know when I do. However, it should be noted that it will embargo during the Nightlife Event.
Again, these were two packs made specifically around the Nightlife event and they work a little differently then some of our others have. When messaging this we were treating it like we do a normal pack and messaging an embargo approximately 1-2 weeks out.
I hope that explains the embargo timing.
-eric