Hi Rick,
Although I'm not a doctor, I can point you to some good information about what exactly a "normal" PSA means. Although 4 used to be viewed as a cut off level for what is considered normal, this isn't a one-size-fits-all answer.
As many as 15% of prostate cancer cases occur in men with a PSA under 4, so it's important to take into account your age, PSA density, percent free PSA, and other factors such as ethnicity and family history of prostate cancer. You can find out more in Dr. Motola's article:
What is a Normal PSA?