In the process of fixing a blown head gasket, I looked at one of my rocker arms that was off centered on the valve and I noticed that the pedestal insert was cracked. I removed all the rocker arms and inspected all the pedestal inserts and they all had a hairline cracks in them. What could have caused this? I bolted them down to specs when I first put the cylinder heads on. Did I over tighten them? What do you guys think?