My dentist didn't take an x-ray of my teeth, but make a molding. should i be concerned?

Moulding for what: What was the purpose of your visit? Was this your first visit to this dentist? Did he have existing records such as X-rays from a previous visit? Was the moulding to fabricate a cap or for a retainer.... Can you be more precise, it is hard to say without all the facts, please ask your dentist on you next appointment.

You should: Before any dental treatment, you always need a check-up and x-rays for decay or gum problem. even for your bite evaluation the x-rays are the standard of care. Ask your dentist for more information. Most likely x-rays are on your treatment plan list.