It isn't clear to me from your post how many pelvic lymph nodes were dissected. Taking out just a few is not enough in high risk cases. The fact that it has already been found in at least one would lead me to believe there were more that were not detected surgically. You may want to read the following:We're still not very good at finding cancerous pelvic lymph nodes
While lymph nodes filter out some of the cancer cells from the lymph, there are likely many cells that get by each node. It is certainly true that enlarged misshapen LNs are a sign that the cancer has proliferated more at that spot, I don't think there is any way to rule out that it is micrometastatic elsewhere within the pelvic LN field. Micrometatsases don't put out much PSA, if at all, so an undetectable PSA is no guarantee that they have been removed.
Adding to the quandary is the fact that detectable LN progression is very slow at first. It is not unusual for there to be years between the first detectable LN and the next one (but that does not mean that there isn't stuff going on below the limits of detection). I don't know whether adjuvant PLN salvage is more effective than waiting for uPSA to become detectable, or whether one can comfortably wait for a PSA of 0.03, as one can with prostate bed salvage. In light of all these unknowns, I agree with those who suggest you begin discussions with an RO about
adjuvant radiation and hormone therapy. Michael Zelefsky would be a good choice.