Most of us have had labs at some point in our hunting careers. While some guys count their ducks on websites like this, I can count my labs. 3 black, 4 chocolate, 1 yellow. I can tell you that your question has the possibility to get a different diagnosis with every response. Usually OCD starts to become visible at 6 mos-1 year. Could be hips, shoulders or hocks. Dysplasia is a possibility. Or an injury. My suggestion is: Let a vet diagnose your dog. If you don't get anything from your local vet, get a second opinion from an orthopedic vet if the condition continues. Just my two cents. Good luck. I hope it is just something minor.
Duck dogs go to heaven too.