Hi Ya Doug,
I'm decently informed on testosterone but not an angel by any means 
Your PSA rose somewhat. Guess I'd have to say I, personally, would have wanted some sort of evidence there was cancer present before agreeing to further treatment. To add to that thought, I do understand. When a man has gone so long without a detectable PSA, any rise might be alarming to him. The PSA fluctuations puzzle me a little. My first reaction would be to say there was/is prostate tissue present but, who knows? Doc's make the big bucks for a reason!
The prostate organ does not have clearly defined borders at the apex which is "one" reason the excision removes surrounding tissue. Remnants of tissue left behind during surgery is common. From what I understand, tissue left behind may cause slight PSA, often represented as slight fluctuations in readings, making it more of a challenge to diagnose a recurrence. Time and doubling time and perhaps ultrasound (or some such test) are the only tools available to help rule out a recurrence.
**Testoserone does not cause, but it does fuel any cells present. If there is / was any of them buggers left, it was likely in the prostate bed so radiation was a good choice. Your PSA since is pretty good evidence of something local, not systemic. The very good thing is, you appear to be a cancer free man!
Be Well, Swim