I don't know if the mat in question if an Olfa, but here they admit to the stinky problem and have a suggestion as to how to deal with it:
http://www.olfa.com/CustomerserviceFAQ.aspx#m3
"How do I reduce the strong plastic smell from my new rotary mat?
Due to production and distribution, a new OLFA rotary mat can emit an odorous smell that some people are sensitive too. To overcome this smell, we suggest that the mat be wiped down with a solution of equal parts lukewarm water and white vinegar, then let it set for five minutes. Afterwards, rinse off the mat and towel dry. Repeat as needed."
It's a shame that this issue isn't remedied at their plant so we don't have to suffer the consequences. Hope this helps.