At the start of Mirkwood you are playing in a layered / instanced version of the area. After completing that quest, you're moved out of the instanced version of the area and back into the main world where you can then pick up the other quests, but can no longer complete the quest from the instanced area so they are removed.
From memory there were certainly more than just two other quests you can do in the area, I just ran the quests until there were no more to pick up upon completion before doing the Hilltop assault to move on. (Though maybe all the other quests I can recall were part of the epic line, not seperate ones?)
Yeah...there are 6 from the same guy before Hilltop Assault and they are part of the epic questline.....so you basically have to do those first to proceed in Mirkwood.
Thanks for the replies...I am already well past the intro Mirkwood instance....I like Mirkwood....it's creepy just like it was in the Hobbit....the book that is...I thought that was the best part of the book