“Few months ago Anet updated character models, giving them ability to move their mouths when shouting, aquaring boons or talking etc.
I noticed that my character doesn’t do that, which is strange, since i remember that it did worked before.”
http://www.reddit.com/r/Guildwars2/comments/1s928g/characters_no_longer_moving_their_mouths_when/
“I noticed this a few patches ago, I believe it was with the Nightmares Within update that they broke this functionality.” – LasurArkinshade
It seems like all npcs have this bug. Most of players have it bugged tho.
Ranger pet needs mechanic changes.