As in most "trickster tales", it relies on the "tricked" characters being complete idiots. For me, this doesn't paint the trickster as clever or intelligent, just lucky and dishonest. If the mouse wasn't trying to save his own life, this would have a bad message, but as it is, it's just middle-of-the-road. It's perfectly reasonable to lie to somebody to save your own life.
Message
People who try to hurt you are stupid, and will fall for obvious tricks.
