thanks to both of you for your comments. After looking at the worn cam bearing with the shop mechanic, it was probably caused by running the engine with low and dirty oil. the one time I miss an oil change and it bites me on the backside...........an expensive reminder to keep up those regular oil changes especially in the higher mileage years of a vehicle. Still, it's curious that only one bearing seems to have been affected. All the others showed no signs of wear.
Joe