gudgeon pin contact surfaces question

glen english LIST

Hi. All (6) my pistons show, pretty much identically :

wear in the gudgeon pin mating surfaces on the piston.
On two sides opposite each other per end. perfect symmetry everywhere.

It tells me where the thrust has is taken up. . Not much, but you can feel it with your finger. 400 hours.

The pins fit nice and snug , no play in any direction with oil in there.
Have kept pins matc hed to pistons (like everything else)

Normal ?
Had film of carbonized something on the sides in there which I got off, nice and shiny now- where the thrust hadnt been (sides) .

finally now have the ring grooves clean. top ring groove had carbon hardened like diamond....