Devon has thrown up in the car two days in a row now, both times on the way home (once from the car wash and today from the vet). Before, he never had any problems and had been in the car at least a half dozen times, although it's been about three weeks since he was last in the car. He was four months old yesterday. Is this a puppy stage thing that they grow out of, or am I looking at a potential lifelong problem? I go to Florida every winter and that involves an 18 hour drive each way, which is why I ask. My previous Sheltie, Baron, never had any issues in the car.