Pantheon Q bug

Hi, I played Katarina Against a Pantheon And an Annie, I'v baited them, then I used "Shunpo" on my mate to go under my turret but I don't think I was on the range of his Q before that Shunpo, he didnt mooved from his position but his stun touched me and I was stunned under turret with the damages without any reasons. Maybe his using of Yumuu placed him at the limited range but when I was shunpo He shouldn't be able to stun me. Or he would be on me.