In addition to state laws, there maybe local laws also. Your local library may have these laws available for your viewing or at least know who to contact in your city to find out.
You may find a contact at your local Home Depot or Lowes that can give you an idea as to how strictly they are enforced. Best to be extremely cautious. Regardless of whether you did a prefect install or not you could still be liable if you haven't jumped through all the correct hoops. Even if not required, being bonded is a very good idea. It does more than just look good on a business card and is relatively cheap.
e.g. A photographer that made a business of photo documenting valuables in homes, would be crazy not to be bonded.