What is she even doing up after 11PM? Marvolo put Harry to bed hours ago; perhaps he should be keeping a closer watch on Hermione as well, who pokes her head in cautiously and then steps through. She’s more cautious around him since the incident about the horcrux, of course, but that should eventually fade so long as he doesn’t reinforce the fear. In light of that he makes certain to wipe his face of his annoyance at the French before inviting her in.