Yes, this is perfectly normal, and is nothing to worry about. We aim to provide you with a product that fits securely, we recommend in this situation that you soak your instasmile in warm water for 10-15 minutes and insert it again and this should feel better.
Remember that your instasmile is custom-made to your teeth and as such will only fit your mouth. If your veneers become loose or uncomfortable to wear and you are within your 30 day manufacturer's warranty then please discontinue use, and contact us immediately. Do not cut or trim or attempt to alter your veneers in any way as this will void your warranty.