not sure, but I completed it at the same character level I accepted it at.

I've tried everything from resetting it to relogging and nothing has let me enter the mission door yet. Guess I have to wait a few days and see. I submitted a GM ticket as well. *EDIT* moving on and progressing my class story as well as giving vette more gifts unlocked the instance for me and I was able to complete it.

I'm lv 33 right now with my marauder, and I've had a blast doing everything from solo questing, to heroic quests, to flashpoints, to pvp all as carnage.