Kalista Ult Taking an extra second to grab player

So, earlier today, I was playing Kalista with a buddy (playing Gragas) against a Morde, Thresh bot lane and I noticed the time it took to pull my support was longer than it usually did (1 second or so). It looked really weird because the animation of the fog going to grab him would just turn around without him, and then he'd be pulled when the fog reached me. This happened several times so I do believe it was a bug.