I was doing the quest A Night To Remeber with my riekling. We went it alone until we finished talking to Ysalda and went to recruit Serana (who may be important since she uses conjuration spells). Then we went to the mage tower and killed everyone outside. Next, we went in and killed the two conjurers in the room next to us and i turned to see the riekling with both hands raised but with a conjuration looking spell in his left hand. This made me burst into laughter and look up the glitch. Strangely enough i found no results of any similar glitches, not even on the forums yet. Now im here asking if anybody has seen anything similar or knows what could have caused this. I think all the conjuration users (necromancers, Serana, and even me) may have messed up the rieklings files or something technical like that.
NOTE: This wasn't a one time thing, it has happened multiple times around the world. Also, he has never actually summoned any atronachs or undead.