It's been quite some time since he's done something like this. Made love in an office chair, or anywhere other than the bed. He'd thought that sort of thing had disappeared with his youth, but Abigail is constantly surprising him like that, drawing him out of himself and sparking his passion in the most unexpected places.
So he thanks her by lavishing kisses on her, stroking his fingers along her thighs, up her spine, wanting to touch as much of her as possible.