Seems to be some minor glitches with any crafting/gathering instructors, your skill levels, and any possible additional quests that they offer.
Heh, I was lucky - I took my toon to Pioneers after having finished up on Elf Island and started the quest chain there, then logged off and worked it more another day. The first time I went in she hadn't quite popped lvl 20 Herbalism but she did so while wandering around the area and I took her back to Varanas to up her skill so she could keep earning exp when gathering.
From what memory I have and how things seem to run, I must have gone through the gathering skill quests in Pioneers on the first time around but stopped before doing the Protect My Throat chain and upped her Herbalism before going back to it, otherwise she likely would have been stopped dead in her tracks the same way many toons had been on Elf Island, unable to continue the main chain of quests.
She's an Alchemist as well - will make sure I grab that quest before she gets too high in Alchemy, just to make sure.