Biochemical Recurrence (BCR) after prostatectomy has been defined as PSA rising from undetectable < .1 to .2
Generally accepted stds look for a trend over time of rising PSA.
Helpful references may be:

SPPORT trial

PCF.org video Jan 2023 "Rising PSA following initial treatment"

If trend/increases continue, Radiation Oncology and/or Medical Oncology consults are appropriate.

There is information that if PSA rises, sweet spot for additional treatment is PSA of .2 - .4/.5

There also is a trend toward initating treatment at lower PSA readings.

Summary: See Rad/Med Onc and follow PSA in 2/3 mos increments to watch for trend.

Best wishes