Did you show the king the letter as well?
I think the wine quest can get left unsolved depending on what order you do things to get it. It is just a cosmetic problem, though.
Mpenzak does lament incessantly about his cart, doesn't he? <img src="/ubbthreads/images/graemlins/badsmile2.gif" alt="" /> When you first went by the burning cart, there should have been a crowd of spectators, and a city guard you could report whats-his-name's attempt to pay you to sabotage the cart.
Is the quest not solved, or is it solved but you still have speech options about it? I think those left-over speech options were cleaned up with the 1.34 patch. Similarly, you could still tell Rob you needed more time after completing the thieves' guild quests.
When you go to the unknown areas, your quest log gets reset.