Hi Phil,
I know what you are going through, the same thing happened to me this year. After all my post-op PSA test came back <0.1 undetectable, in January of this year, my test came back at 0.1. We took another PSA test 6 weeks later and it was still 0.1. Then at the end of March we took another test and it came back <0.1 undetectable again. The same lab has done all my PSA test the past 2 years.
Now the first 2 months of this year I had a bad sinus infection. I was put on antibiotics and the last PSA test was taken after finishing the antibiotics. I still don't know if this had anything to do with it but I remember having to take Cipro after high PSA results before DX to see if that would bring down my PSA. It did, but not by much. It didn't take much to bring me back into the Zero Club this year.
I have an appointment next week with my uro and I plan on discussing it with him. Maybe that is what happened to you.
I agree with An, maybe you need to be tested every 3 months for now to keep an eye on things. I get tested every 3 months since my surgery because of my positive margins.
Keeping my fingers crossed for you! Don't be a stranger around here, I am sure you have a lot to share with the newbies.
Bill from Florida