I get the exact same reaction from people when they see my 3 month old dalmatian/akita mix. They always assume that she is a black lab and that she should be fat because she is a puppy, however, she looks almost exactly the same as your puppies in her body structure. I must say though that I too once beleived that puppies are suppose to have "baby fat" and if I saw a lean puppy I often thought that it was underfeed or sick. I know now that I was completely wrong on this, but it is a common misconception among many people.