Sam follows Dean into the room and does his own poking around, wondering if he should be able to - he doesn't know, sense something or something. For the moment, though, relying on his eyes, and catching nothing out of the ordinary. Eventually, he straightens and follows Dean's eyes to the quill.

"Where's the knife you were talking about?" he asks, voicing that particular thought. "The one that tried to stab you?"

Erasing previous candidates in his mind and trying to sort through potential new ones, but of course it could be something entirely new they've never seen before, that's always a possibility.