Well I'm not trying to lie, two things could have happened. (To bad I infused that one) 1. I might have confused secret round perk for it. (Looks the same) 2. I was extremely lucky and it did drop for me. I can still recall naming it out to my friends and they were like okey nice. But the other perks were crap. So I have no proof since I infused all but the one I liked most...

Not trying to be a dick just letting yea know it's not a possible roll maybe the game glitched and dropped you one with it but it'd be the only one I had seen or heard of with 10 hours of grasp grinding this week and probably 5 times that in weeks prior