Conrod bearing shells can wear with time. They develop little wiped areas where the crank journal momentarily contacts bearing surface. Once in a thousand starts, you'll have a hot engine with hot, thin oil with minimal lubricity started and throttle-blipped before oil pressure can build up. A just little touch, but a coup-de-grace that can happen a dozen times in 100,000 miles. Or even a couple of "aw-sh%$" oil filter o-ring incidents. Not enough to increase clearance or damage the bearing, but wear nonetheless, and it adds up. On my bike I've replaced the conrod bearing shells every 90,000 miles. Not abnormal and not a big deal.
What does this look like? Imagine the bearing shell is freshly painted with aluminum paint. Imagine dragging your thumb across the wet paint.
Yeah, we need pics.
'73 R60/5 Toaster