Cassiopeia's ult on Tibbers makes him stutter. (Idk about other pets/creeps)

Hey, so I was playing ARAM and noticed that Tibbers stutters(kinda wiggles around in the spot) when ulted on by Cassi. This was yesterday, and it doesn't affect the gameplay however I remember seeing a similar situation before at the PBE when Bard's ult was doing the same, and it was said to be patched. I think hers also needs a look. Thanks.