He hadn't really expected anything to happen; that spell was unlikely ever to detect anything more sophisticated than student-level work. ... On the other hand, he doubted if there had been anyone more dangerous than students at Hogwarts for the past fifty years. Not that some of them hadn't been outright menaces.
So when the box shifted oddly, he raised an eyebrow - until he realized that it hadn't really distorted the way it had appeared to. It was just constructed strangely. After muttering a few more quiet words over it (one could never be too careful about imbued curses, as the erstwhile Headmaster could attest to), he set down his wand and picked up the box in one hand. "Safe, I think," he said, nudging at one of the corners with his thumb and feeling it buckle slightly under the pressure. He wondered idly how many pieces there were. "Unless someone's left something unpleasant inside. But if they cared to send you something dangerous, they might have chosen a more straightforward method. Whoever it was," he continued, placing down between them on the desk again, "Seems to think you have a lot of time on your hands."