[Stiles shakes the curtain out and examines both the cloth and the area around it to see if there's anything else he might have missed.]

Maybe Poland thought it was a clue to opening a new secret passageway and we're missing a note that told him to eat the poisoned curtain. [His heart's not really in the sarcasm though.] That note just screams of a murder plot to anyone with half a brain though - if it was real, I don't think he would have fell for it unless it was delivered by someone he trusted.