"Of course it's necessary." Though he doesn't elaborate on why. He keeps brushing off sand, moving gradually from her arm down her side and then trying to coax her to sit forward a little so he can get to her back.

"Hmph. Do I look comfortable?" He really doesn't, the way he's holding himself as he sits. "Do you have a hairbrush? Otherwise I'll have to use my fingers." To brush the sand out of her hair, presumably.