Have you ever heard of such a thing as moisturizing your cutting mat? I found this on Generations Quilt Patterns. Here's what she had to say:
To soak it, put your mat in a bathtub or large container (would have to be large so it can lay flat) and soak it for 15-20 minutes in a solution of 1/4 cup white vinegar to every gallon of cool water. Let me repeat, cool water. Do this every so often to help extend its useful life.
Then use a squirt of mild dishwashing soap (Ivory) and clean the mat with a mushroom brush (soft is the key word here). The purpose of this gentle scouring is to remove the fibers that get trapped in the cuts marks preventing the cuts from "healing".
Keep 'em clean, keep 'em moist, keep 'em flat and NO heat. Your cutting mat is not a coffee cup coaster!