My cat seems to be drooling, is there something wrong?

My cat stays outside, and has always been healthy. He is neutered, and has no fever. He doesn't have any nasal drainage, or eye congestion. His breathing is clear and steady. He isn't sneezing or coughing. He has plenty of water and food...but he seems to be drooling excessively. Could this be a serious problem? What could be the cause, and the "fix" for this?