As far as I know the dwarf mines have one really stupid moment in their questline: when you get the quest to get a stone plate/figure (or something, I'll call it "whatever-you-have-picked" for shortness :p ) from behind the last boss in the instance then you *have to* click on the "whatever-you-have-picked" in your backpack and accept a new quest BEFORE returning the original quest.
The quest you'll get leads to the whole chain of quests, leading you out of the dwarf area without picking the second class, and giving you a few titles.
If you return the quest for "whatever-you-have-picked" before clicking on it, the "whatever-you-have-picked" vanishes from your backpack and you have no chance to get the quest (and the whole quest line). Really, really, really irritating!

Really!