hank wrote:
almost new honda generator leaks a small amount of oil from one of the
bolts above oil filler cap on exhaust side.

if the attached picture shows, it's the bolt with arrow point

can just this one bolt be removed and resealed? the amount of the leak
is very small, after generator has run for at least 30 minutes and power
generation is working normal.

I would first check & correct the oil level.
Then I would re-torque all the bolts in that cover to factory spec.
If seepage still occurred, I would make a fiber washer and clamp
under the head of the bolt.

--Winston