The mat tends to develop static. I got a can of Static Guard and sprayed both sides of the mat; works great. Some websites said to rub a fabric softener sheet on the mat. I tried that too, but it didn't work for me.
Another tip, until you can get the Static Guard, is to lay the die upside down so you are lifting the die off the mat instead of lifting the mat off the die. This helps, but I always forget to do it. I like the Static Guard better.