It's a bit more complicated,
PC: Dracorid3r,
Character: Frogo Underhill
Quest: Garden Plot
So, a character Calis Smith, crashed and nearly died, he came out of the quest. Another character was able to take it, and finish it. (not being in the same party as Calis) Calis logged in again. I think he tried to take it, and was unable to, saying it was over for him.
I took the quest, (Without Calis) and yet Calis was able to come into the quest with me, though I was the only one in the quest party.
This has happened somewhat similarly with the cheese warehouse quest as well.