‘ And it was so, for he rose up early on the next day, and pressed the fleece together, and wrung the dew out of the fleece, a dish full of water.'
God graciously provided him with the sign he requested, so much so that a whole dish full of water was wrung from the fleece while the ground was bone dry. He was promised the dew of heaven.
But then he realised what a fool he had been. The fleece would naturally retain the dew, while the ground around may well have had time to dry out. He should have asked it the other way round.