It may be worth considering that the PSA assay may not be totally precise. Recently I had two separate blood draws within a minute for PSA testing: one blood sample was assayed at 0.43, the other at 0.47 (so a variation of 0.04 or 10%). The blood draws were from the same needle and using the same type of vacutainer etc. etc. The implication being that the assay is accurate but only up to a point. So it is easy to understand why, as Lyn said above, one of the elements for diagnosing recurrence is three successive rises.
Good luck to you both