Zed+super minion bug

So I play zed a lot, and recently i've noticed something odd. While clearing a wave with super minions in it, the super minion just stops. I never checked if it was after a certain ability, but i've had about three games where I could clear a wave and leave the super minion just standing still in lane, near base, anywhere on its movement path. It's great for me, but it really takes a lot of pressure off, being able to back and deal with it later. Note: after attacking the super minion while it is standing still, it returns to normal and keeps marching down lane. I don't know if it's specific to zed, or has a certain way to reproduce it, but i would suggest taking zed to the rift and putting him against some super minion waves.

Second note: I don't remember if this happened in other lanes, but the times i do remember all happened in bot lane.