What you just asked
Is my cancer back?
My guess is the doc will tell you it may never really left your system entirely but the micro specs of it are so indolent that it took two years for your PSA to go from .03 to .04. He may also say at such low test result levels it may be .03 today w another test just like the previous one had that registered .04

I'm sure your doc will have very reassuring news for you
Good luck!!