were you using a 60mm cutter? or a 45?...the 60mm is larger and works better for thick fabrics...you should never have to put alot of pressure on a rotory cutter- if you are pushing hard enough to damage your mat you are pressing WAY too hard! do you have the correct blade for the cutter? did you turn the (screw) on the cutter too tight so the blade can not roll smoothly? also...fleece is (hard) on cutter blades! it dulls them quickly---scissors are sometimes a better choice.