2002 Pathfinder DTC P04030 Code Followup

2 months ago I replaced a leaking front tube assembly CAT on my 02 Pathfinder (which couldn't be patched w/ the Nissan kit). After replacement and resetting the emission control unit, the P0430 code did not return. However now 2 months later the P0430 code has now returned and in shorter mileage intervals. It remained off after the initial CAT install for 1200 miles, then after reset it remained off for another 500 miles, but now it remains off for only about 100 miles. Other forums have suggested that I need to have the ECU programming updated at a Nissan dealer to make it more tolerant of O2 deviations from spec. Does anyone have any other suggestions before I take the machine over to a dealer?

Thanks in advance. RJ