I have a pair of Draggin Jeans that are around 2 and a half years old. They have kept in good condition as far as the stitching etc goes. Except for around the cuffs where they have torn through.. They get washed irregularly and hung out to dry in the shade. Does Kevlar have a "shelf life" where it basically isn't what it use to be ? Does it degrade overtime ? What are the signs to look for?