In my (not exhaustive) testing, friends will cause npcs to go aggro **IF** you are standing near them when it wears off. If you go away and return later it is fine (again, as far as I was able to tell). If I recall correctly there was a note about this in one of the early patch notes after release.
I can confirm that they won't go hostile if you get the f. Out from there in less then 10 turns. I think the implementation is bad it should be like mind reading roll a dice if you are successful you won't get caught.
