Yes, do it now. Most of us underestimate our own habits. She is observing something about your behavior that seems related to bruxing your teeth (or more commonly clenching your teeth). Vist an excellent bite dentist or TMJ dentist to get the fastest results. You will have less stress with your wife if you go ahead and make an appointment.
Yes. Yes, at least evaluated to see how much of a problem it is. See TMJ expert. Any dentist can be a TMJ expert with the proper training and experience. Most commonly, oral surgeons, prosthodontists, and orofacial pain specialists. Ask your MD, your dentist and your dental society for referrals.
Yes. Bruxism may not be causing any discomfort at this particular time in your life, however the damage is being done. Muscles, joints and teeth are all involved. Pathological tooth wear can result in a myriad of future issues which may be very costly. An orthotic can prevent or retard the adverse effects of this habit.