A reputable breeder will want to know as much about YOU as you want to know about them and their dogs. This is a person who you will hopefully have a relationship with during the life of your new dog. Do not be afraid to ask lots of questions about the puppies and their parents, such as any health problems in that particular bloodline. Most reliable breeders only breed a dog once or twice. Many times only the mother of the puppies will be on site.
Some breeders use males from another kennel to strengthen their kennel's bloodlines.
This is nothing unusual. It is unusual, however, to not have the mother available to see. Puppies need 3-4 sets of vaccinations before they are fully immune to many diseases. Puppies should be at least 10-12 weeks before you take them home. They need time with their mother and siblings to learn social behaviors.