User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-4132454-20130407213002/@comment-1837917-20130408085316

Could it be in relation to fighting Brachydios? Cos' that's what the Guild Sweetheart mentions before you get the quest. She specifically say that the Argosy Captain has requested it to be hunt, so maybe even though you've talked to him, he won't leave till you've hunted it down?

Idk. But it is between the Rathalos and Zinogre urgents.