"I don't lie to you," Hermione pointed out. "And I would not keep something that big from you, either. You really want to know? All I said was that if I did have a book like that, I wouldn't leave it around for you to find anyway." With good reason, apparently. "But I don't, as you've well realised and consequently made a huge deal out of something that really wasn't necessary."
There, he now knew what she had crossed out. That should make him happy.