The once outcast orphan wasn't used to people being scared of him, and he was just getting used to people liking him.
When Morana started, it also caused Mitch to start and take a step forward, instinctively going to help her until she caught herself. Then he retreated a step, just to give her space, but he didn't turn his gaze away. He noticed her long hair first (he'd seen very few people with hair that long, and still rather pretty, too), and then how scrawny and slim she was. No wonder she was in the kitchen then!
"Whoops, I'm sorry for startlin' you," he said with an awkward smile, as he kept his voice calm and reassuring. He stayed just one step away the kitchen door, just in case she didn't want him near. "I'm Mitch."