I've had sabres follow me into a house... don;t know if it's a glitch or whatnot, but if they're like in strike range, there's a chance they follow through loading areas. Was kinda funny, had to go in and out of the house 5 times before they killed my poor mage

. Happened with other creatures too. Same thing happens with NPCs you just interacted and they still are talking, they popup on the other side of the door too. Well at least for me. So they're ya go, try that