he caught hold of her arm. "Hold on- he probably doesn't know-" Realising what he'd done, Clark released her arm immediately. He'd just grabbed her - he could have hurt her. He didn't know his own strenght; he could have pressed too hard, bruised her, maybe even crushed the bone... This is paranoiac!
I agree whold-heartedly. He's going to be afraid to touch/rescue anyone if he doesn't get a grip on himself.
