Severus narrowed his eyes, shining the light from his wand on the girl's face. She looked vaguely familiar, and she was obviously jittery, though he couldn't help wondering if that was only because he had startled her just now, or if it was something else. Then again, perhaps it was a combination of both, he thought, finally putting his finger on where he'd seen her likeness before. She was the girl who had been having trouble sleeping. Chronic sleep deprivation could certainly cause jitters.
"Miss Ashford, isn't it?" he asked quietly, frowning. "Have you been sleeping any better lately?"