New smite vision bug? Possibly I don't fully understand the vision mechanic?

So, in the new season 5 preseason jungle items: the item that grants true dmg upon attacks and a vision debuff.

I was playing hecarim in jungle vs. an opposing wukong jungle.

I caught wukong in his jungle at low health: I proceeded to duel with him. As he used his Q I simultaneously used the new smite granting me vision expecting the W decoy. He proceeded to use the decoy anyway. I lost and regained vision of wukong far from his decoy.

Is this a bug?