First off: I play very casually - been playing since pre-release and my main is level 31 now.
I was bitten by a player at the ritual site back when I was around level 23, got the debuff and the quest, etc. But at the time the quest was too hard.
I read that you can still do the quest even after the debuff goes away, which was true. I checked back in at the ritual site every now and then and I still had the ability to go through the portal and make an attempt at the quest.
I recently logged back in after about 2 weeks of no play and found that my quest was gone and the portal was no longer there...
Am I screwed now? Is this intentional?