There are some hallways and such that screw with pet pathing AI. A good example is in Haukke Manor in the hallway right before the first boss. If you enter the room before it, your pet will fly towards the boss room and will almost always aggro the succubus. You can stop it if you pay attention, and it likely won't be a party wipe encounter, but it becomes more of a problem later when you inadvertently piss off a whole room.