"My boy," Dumbledore said, in a voice that instantly put Harry's hackles up, "You have no idea how exceptional you are, do you?"
Snape's acerbic voice slashed through the saccharine, "I'm certain he's well aware of exactly how famous he is." Snape's voice changed, as he turned towards Dumbledore, "The students stare, did you know?" Harry didn't need to see Snape to feel those eyes sharpen.
Prof. McGonagall started to talk, neatly intervening in the quarrel as if she'd had extensive practice. "You, Mister Potter, are a one in a hundred year talent on a broomstick."
"Filius' charms were rather more adapted to refusing spellwork, yes." Dumbledore said with a smile.
"Then why were there brooms there?" Harry asked.
"That was my suggestion," Snape added. "Not, as you clearly seem to expect, for first years. It would serve as a delaying tactic, to prevent the wizard from simply blasting through the door."
"You three added three degrees of autonomous movement to my chess puzzle," Prof. McGonagall added. "I assure you that none of the professors here, with the exception of myself and Severus, could solve it by themselves."
"It would be highly unlikely for anyone to manage to subvert three teachers at Hogwarts," Snape said.
"Then why did you have Hagrid-who-can't-keep-a-secret-from-first-years design a puzzle?" Harry asked, his nerves and frustration fighting getting to get hold of him.
Snape smirked, "Opening a door causes an alarm, as often as not. So too, here. The alarm quiets if the door is closed again, which, I admit, is not the best security - but it is the least detectable sort."
Harry wasn't sure he believed any of this, but he was certain that they were making a Grand Chessmaster Gambit. That would bear thinking about, whether or not he believed it. In the meantime, he wanted his friend. Her perspective might shed some light on the matter.
[a/n: Yes, there's a reason the logic puzzle wasn't mentioned. It's been my pet peeve that people say "but three first years could get through it!" This is a different stab at it. Please leave a review? Note: snape does not say it is impossible to subvert three Hogwarts teachers.]