My knees pop after running. There is no pain. Is this early arthritis?

Tendonitis. If they cause a problem after the running is is usually a residual inflammatory process not arthritis . Could simply be a tendonitis an could be shoes or gait . First try to make sure the surface you are running on is level. If on a street if you only run on the right side you right leg is on the down side run back on ie same side you were on so left is down, try Motrin prior to running. See md.
Knee pain. This could be chondromalacia patella (softening of the undersurface if the kneecap that gets inflamed with extending/flexing knee). After exercising ice the knee 10-12 minutes then perform hamstring stretching and stretching to the iliotibial band (see iliotibial band stretching on google). Good luck.