Even though she'd just said that she didn't know that Harry was here, the first thing he'd thought when he heard that she was at the Sanctuary was that she was here to find him. To drag him back, to scold him, to shout at him... any or all of those things. And even though she'd just told him that she'd had no idea he was here, that hadn't registered as deeply as it should have and that thought still lingered in the back of Harry's mind. It put him more on the defensive than he already was... God help poor Ginny.
Walk. He could walk. He would rather go back to his room and shut the door so she couldn't follow him in... but if walking was the only alternative to standing there awkwardly in that hall, he would do it. So he nodded once before lifting his eyes back up to her face, and he would take enough initiative to head forward past her, down the hall and back towards the stairs. They certainly weren't just going to walk around the inside of the Sanctuary, they were going to go outside if they were going to walk.