So I was testing Vel'Koz out earlier, and I noticed that several times when I wanted to fire off my Q to secure a kill, it split way before I wanted to, even though there were no enemies in the area. Later, I cleared a wave of enemy minions, and test fired my Q into my wave. It split immediately when it hit a friendly minion. I then fired it off to the side, and it behaved as normal.
How to replicate this bug yourself:
* 1) Find a wave of friendly minions (or just one friendly minion, either works).
* 2) Make sure there are no enemies nearby (or neutral minions).
* 3) Fire Vel'Koz's Q into a friendly minion.
* 4) Watch it split prematurely.
I have not tested this on friendly champions yet, but I was able to recreate this 100% of the time on friendly minions.