GAMEPLAY Rumble E Stuns after Flash??

I was playing ranked yesterday night when rumble came back out and encountered something i assume must be a bug. This has happened to me 3 times in 2 different games where when i flash towards rumble, he uses his E immediately and it stuns me for a short duration instead of slowing me. It happened to lose me those 2 games. If anyone can look into this and provide feedback that would be great. Just to recap- Flash toward rumble, have rumble hit you with his E right when you reappear from flash, check for stun. This might be me just seeing things but since it happened 2 games in a row im very confused.