Hermione was already back. She was trying to stay 'home' as much as possible to avoid a repeat of Rose with Hugo or Ron, not that she thought it was even possible with them. Then again, she hadn't thought it was possible with Rose.
When Hugo arrived, she put down her book and smiled. "No, I'm still at the office," she deadpanned. "You sound excited. What happened? And if you tell me that they cast the Imperius on you, I might have words with a few people."