Professor McGonnagall frowns slightly at that question, glancing at the door and then lifting her wand. There's a shimmer of magic and then she gives a nod.

"It's only us then, but what has you so worried, Mr Potter?" She glances to Hermione, arching a brow.

"Professor, if we told you there had been an enchantment on us, would you be able to sense it?"

She nods. "Though it's not common for test for such thing on students. Especially first years."