When my rotary cutter starts missing a few threads I change the blade and the problem goes away. But I do think mats wear out, dry out and get small pieces of fabric threads stuck in them and over time that is bound to cause cutting issues. Have you turned your mat over and used the plain, unlined side? I have 2 green Olfa mats and have had them over 5 years. I can tell some spots in the middle where I cut a lot are starting to wear, but I feel like I have gotten my monies' worth so far!