Layman out on a limb here: I had extraprostatic extension (EPE) post op pathology. It was a negative finding and in fact my PSA was "persistent " ; not below .19
So I had Salvage Treatment of radiation and short-term ADT and have been undetectable for a year.
Your finding may foretell an ncreased risk of BCR at some time; or not.
Follow the PSA tests and IF your PSA rises then there are treatments.
Hard not to be concerned, but so far so good and it may or may not recurr.
Be positive and enjoy your current status; undetectable.
Best wishes to all.