in the past week my cat lost his upper front tooth (incisor?), I'm not sure how. Should I take him to a vet, or is this something that happens to cats sometimes. He can stay inside whenever he wants but usually wants to go outside, and we live in the countryside so that's not a problem. He's about 3 to 4 years old, had his rabies shots, and doesn't seem in pain, I saw the missing tooth when he was yawning. Should I be concerned?