"Tell me what you dreamed about," he says, distracted, as he tries to discern the best way to remove her dress. Over her head seems the best option, as there's no zipper to undo to simple allow him to push it off her shoulders, and he wants to be able to touch more of her.
And so, after gesturing for her to lift her arms, Hannibal pulls the dress up and off and sets it on the desk so he can concentrate on pressing kisses and stroking his fingers over that gorgeous freckled skin.