This has been reported in the past but I haven’t seen it posted here in regards to retail, so:
Whenever advancing through an NPC’s dialog, it triggers their “goodbye” clips. They say their hello when first clicking on them, but when clicking “Continue” they normally shouldn’t say anything, but instead I get the first of two or more goodbyes in a row, depending how many quests I have to turn in.
From what I’ve read this doesn’t happen to everyone but I haven’t seen anyone figure out what those experiencing the bug have in common.