64,
It is entirely possible you have a block with poorly machined lifter bores. This would cause cam failure even if everything was perfect, and is never checked. I don't check for it either, so I wouldn't beat yourself up too much over it if that's the case. This is a real problem with Hughes' cams over the years because they are so aggressive on the rate of lift. It's also why I shy away from max rate of lift cams for street builds. .