I was doing the Forbidden Legends quest and was heading to Geirmund's hall with Brelyna as my companion. We were fighting draugr in a narrow place and I accidently hit her. She turns on me and is trying to kill me, almost did before I realized what was going on. So I killed her, got some message about go back to the College since I'm arch mage. I had to try and finish the quest I was on because there was no other way out. But I got killed. Since I hadn't saved my game it reset to before I killed her, we went on and everything was fine.
Was this normal? I've never had a follower try and kill me if I accidently hit them, they just say " watch out" or something like that.