I originally went to Quessa-Uss before finding Derenton Freehold, where I was given permission to enter. When I talked to the Drakon there, I was granted the permission to enter. Much later, I talked to an NPC who told me that Greta was captured (which I believe should have happened prior to getting permission to enter).
Now, the drakon at Quessa-Uss Gate says that I don't have permission to enter.
I could just attack him, but I think that there's a trigger that should have fired, but didn't.