I had this happen with the Olfa mat I purchased at Joann's once. I can completly relate to your problem, mine smelled darn close to ...Skunk! I saw the Olfa rep at a International quilt show and asked him point blank about the smell and how to get rid of it. He told me to soak it in the tub with vinegar, well it helped a little. What helped to most was leaving it in the garage for the winter. Yeah the garage smelled for awhile , but I could not bring myself to throw out what was an expensive purchase.
I think that the placed that sell alot of mats , they do not have time to breathe and have the smell go away. In hind sight as I was driving home from purchasing mine , I thought I had come across a receint road kill skunck because my car smelled.