D.C.
My daughter has a clogged tear duct, and the symtoms are exactly as you describe. The only difference is that she's had hers since birth, and most other people who's babies I know who have had clogged tear ducts have also had them since birth. I suppose it's possible to get them when you get older. We're just supposed to gently massage the tear duct and it's should go away on it's own eventually. You should see the pediatrician about it, though, if it continues, so he can show you how to massage the tear duct if that's what it is. My nephew's tear duct did not clear up on it's own, and he had to have surgery. It was very minor surgery, and he recovered just fine. Hope it clears up soon for your son!
D.