Yorick's Maiden of the Mist Bug?

Hey all, I played a game with Yorick and was split pushing with his ult up. When taking down a turret, I noticed that the Lady of the Mist was taking the damage, even though there were minions and she had not recently attacked an enemy champion. Perhaps this is just one isolated incident, but I just want to put it out there to see if it has happened to anyone else.