the Fluffy fiasco

Last night at 4 a.m. we heard an animal in the bedroom. I pointed a flashlight at the little scratchy noises and saw that Fluffy, our resident pet hamster, had somehow escaped from his cage. He looked very healthy and happy to be having an adventure. He had travelled the equivalent of several hamster miles. Lisa picked him up without difficulty. We walked him back to his cage, and saw that a piece of the plastic exercise wheel had broken away, explaining where he escaped but not necessarily how. His water bottle was empty and apparently he was extremely thirsty -- raising the question, did his thirst drive him to bust out, or did his adventure make him thirsty?