"It has nothing to do with you being a girl, or not being tough.  Just because you're tough, doesn't mean you can't get hurt, and it doesn't mean I don't worry." he said.  "Just because I'm worried about you doesn't mean I don't think you're tough.  You could have a quirk that made you impervious to all damage, and I'd still worry.  You could be stronger than Deku, and I'd still worry.  So don't get ideas in your head that I think you're weak, because I don't.  But no matter how tough and strong you get, I'll still worry."