If it's defiantly a squeak (not a processor hiss) it's probably a fan. On of my front fans sounds exactly like a hamster wheel, it just needs lubricated or replaced. Contact AppleCare if it really bothers you, they should be able to send you a new one depending on which one it is.

On another note, I've heard of a few cases of the liquid cooling system leaking. It is entirely possible. Think of it as a mini car radiator (cause thats what it is). There are entire shops dedicated to radiator problems and repairs.