[Schortt]

Sentries are on coldain faction and Sentinels are on Dain faction, which probably explains why this is happening (sentries are one of the few mobs, along with Councilors who are on Coldain faction in keep part of Icewell). I've noticed the same thing with other cross faction mobs running. For instance, Grand Huntsman Darral (Dain faction) runs when you have him and Royal Armorer Slade (Coldain faction) aggro'd when Darral gets low HP.

Whether or not this should happen is another question. I honestly don't remember from live and in prelim research haven't seen anything to suggest one way or the other.