Mike,
Older guidelines placed biochemical recurrence (BCR) after you have a PSA of 0.2 after primary treatment with prostatectomy. That was the guideline when I had my salvage radiation 5 years ago, and may still be the guideline recognized by many doctors. But the newer guidance from the National Comprehensive Cancer Network (NCCN) is to assume BCR at a lower PSA reading of >0.03 or increases twice in a row after PSA having fallen to near zero. See the link below to page 66 of the NCCN Guidelines for Cancer Patients PDF booklet. If any of your doctors still follow the 0.2 guideline I'd suggest asking them to discuss if they have considered the newer guidelines, and nonetheless believe the 0.2 guideline is still a better demarcation before considering further treatment. They may well have good reason based on experience or other published studies, or because they may weigh the risks of treatment against the risks of side-effects differently for different patients, based on each patient's particular medical history.
But based on the newer criteria your oncologist will probably recommend further treatment based on your current PSA readings of 0.08 and 0.09. The jump in 3 months may be less significant, because measurements at these low numbers may not indicate actual future doubling time. My own experience when I was tracking my PSA at these low levels before SRT was that I stayed below 0.04 for several years and then jumped to 0.1 and remained at 0.1 for another three years before suddenly jumping to 0.2 and then 0.4 within a few months.
Here's a link to the NCCN Guidelines document I mentioned above. See page 66 if the link doesn't take you there directly.
www.nccn.org/patients/guidelines/prostate/index.html#66Jim