Gangplank Barrels

Recently I've played against a Gangplank in ranked, an if he Q'd at the same time as i Last hit his barrels (I even got the gold for it) they would still go off. I ended up later having the same issues in later games. So my friend and I tested it, an it's mainly on a Q activation. but if he shoots his Q within the time of the opponents Auto or skill that can damage it goes off in animation, even if they get the gold, the barrel and any linked will still go off.

I don't believe that is how this should work as I dont play Gangplank myself, but from what i read in the tooltip an saw in his spotlight, they shouldnt explode if the opponent gets credit for it. It's actually quite a punishing bug especially for short range or melee champs.