[GAMEPLAY] Rengar enpowered E on cooldown

I was in a game as rengar and i had 4 stacks of my passive. I went to gank and used my first E to get the fifth stacks but my enpowered E shared the cooldown with my basic E. This bug only hapenned once and I wasn't able to reproduce it in a custom game. The only replay I have was created with the skinspotlight replay system and I dont know how to upload it.