It is unfortunate that you have detectable PSA so soon after surgery. I have had five tests in the eleven months since my operation, all undetectable.
Recurrence after prostatectomy is officially classed as a PSA of over 0.2, or consecutive increases of more than 0.1 over a number of tests. I think your oncologist is quite right to wait for your next test, as the two results may be aberrations, but I’m sure it will be a very worrying wait for you, on top of all the worrying you must have done upon your diagnosis.
Best of luck however it pans out.