When it became evident that she wasn't going to explain herself any further, Antonin grew annoyed. He tried to hide it, of course, but she'd been his wife long enough to recognize the signs. She made a promise that she wouldn't share the spell with anyone. That included her husband. If he knew how she was able to find him, he wouldn't stop annoying her until she taught him. They were frightfully similar on that score. He was stubborn and prideful enough not to ask questions he knew wouldn't be answered. Taking pity on him, Hermione continued their discussion in another direction.