'02 Pathfinder surges with cruise @80

[epmeyer]

Lately on my '02 Pathfinder LE 4x2, speed starts oscillating up and down by 3-5 MPH while using the cruise control at 80 MPH (in this part of Texas, the effective speed limit through the speed traps is whatever the sign says + 9.9 MPH). It doesn't do it at 75, but at 79 it starts oscillating after a couple minutes at speed. The road is basically straight and flat.

We are within 3,000 miles of driving out the warranty, so now is the time to ask. Is this a known issue? Am I expecting too much of the engine & cruise control to hold 80 with just the driver in the truck?