I agree with Melissa and Franklin. I had one corgi just recently that had some kind of respiratory virus (she had her kennel cough vaccine) but was around other dogs. My previous corgi had mitral valve prolapse (a heart condition).
So my vote is for the vet to check him out.
Franklin also got kennel cough even though he had the vaccine. The vaccine is not 100% and basically just helps the dog fight kennel cough if/when they get it. It can be a pretty serious disease in older dogs or immune suppressed dogs and can turn into pneumonia so antibiotics are recommended usually. For a nine year old dog its probably best to see a vet. Remember its HIGHLY contagious so even if you just took your corgi to a pet store, groomer, or even the vet he can pick it up. Also if anybody was handling a dog with kennel cough and then came and played with your dog, he can get it. Most dogs are infectious and spreading the disease before any obvious symptoms arise. Keep us posted!
Also is your dog on heartworm preventative? Later stages of heartworm disease often present as a cough.