What you need to realize is that shortly after you leave the kennel, things quiet down quickly. Dogs will raise hell when someone new walks in, or a new dog comes in, but they settle down quickly, and the routine staff members don't key up the dogs like that. Things stay pretty quiet during normal routine at a boarding kennel. There are noisy dogs, but for the most part, things are more serene than the environment you witnessed.
Your dog will likely get into the routine of the kennel VERY quickly, and will for the most part forget about you until you come back to pick him up if the kennel staff is doing their job right. His worried behavior may have just been your nervous energy travelling down the leash.
I'll be willing to bet your pup doesn't want to leave the place when you come to pick him up.
