Had the cylinder bored to 101mm and a new Pro-X piston installed at 18340 miles. Had to pull the head owing to a dropped valve seat at 24,500 miles and note this wear on the cylinder: And a shot of the rear portion of the cylinder: The cross hatch is evident on the unworn portion, there was no damage to the valve/seat and running my finger nail across the "streak" does not reveal any surface imperfections, in other words, it is smooth. There is some obvious wear areas in the front as well. The work was done by a reputable machine shop. Regular oil changes were performed up until head removal. Last, but not least, the engine did not burn oil. Do I need to worry about this? Obviously a compression test should be performed but that is not possible now. I have a spare piston with rings (new) for 102mm so I could re-bore but really do not want to with such low miles on the build.... Any input here???