Not necessarily, he may just be anxious from the car ride, excited, or not sure if he is going to the vet to get a shot. Much like kids in pre-school, once you are gone they settle in and get comfortable. In fact, they often pull us into the grooming area! We always allow the dog to roam around and smell the salon a bit to familiarize themselves with their environment.
Dogs are very intuitive and will pick up any anxiety that you may be feeling, so it is important that you be calm and reassuring.