On some it looks as though the edges of the hole have been peened over a little to grip the pins more securely. Perhaps it's only older ones that have been taken apart many times, and the holes have worn a little, that have this. Sometimes you can tell from small patches of wear to the paint which side they were pushed in from. It's probably not that important but the theory is that pushing them out the way they went in saves a bit of wear on the holes.