I don't know how they are shipped to stores but if I mailed one I would want to be sure it was securely packed in any box so it didn't have any room to buckle if the box was put on end. You have no way of knowing what temperature the box will be subjected to either and if it gets really hot then if the mat isn't secure it will likely warp.
If you're giving this as a gift why not just mail a gift card and have the person purchase one locally with the gift card or order one on-line and have it shipped to the person that way it is the seller's responsibility to make sure it is packed right.