on 1.6 at the moment, only mod outside of textures and the likes is the unofficial patch v1.05a. I finished the special job for delvin in the thieves guild about the silver mould from markarth on looking for new work he had the line 'I finished that special Markarth Job.' selecting it he says his piece then it goes away with no noticeable changes. problem came when saving the game and coming back to it later today on loading up the line is back.

does it matter? is it broken? is 1.6 broken? is the unofficial patch broken? etc

I do know that the Unofficial Patch is on to v1.05c beta, as far as I know that one or 1.05b are the ones to use with the 1.6 Bethesda update, I believe the b and c versions were to do with conflicts in dialog changes which were introduced with 1.6. I've no idea if it will cure the problem your having but it might be worth trying.