Gangplank Q Bug

As a new Gangplank main, I have noticed a single issue with his q. When you q a minion for the last hit, if it happens to die in the second that you shoot, the ability goes on cool down regardless of if it was used. Hopefully this is a simple fix, and i'm sure others have noticed this problem.

Then again maybe I'm just horrible at last hitting and you designed the game to ridicule me. In that case, I understand.