My Xikar ELX has a punch cutter built into the bottom, as many do. On the last two cigars I smoked, the cap split a little when I punched it. It was still completely smokeable, but I'm wondering why.

I have punched four cigars with it, so it shouldn't be dull yet. I press the cigar onto the punch firmly but smoothly, rotating a bit back and forth as I apply even pressure. Am I doing it wrong? Is it perhaps my RH is kept at 70%? Does this just happen sometimes?