When did you buy it? You have to open it up and tell us what chipset it's using. This is the first time I'm hearing or seeing a Toshiba SSD in a 2013 Macbook Air. The good news is that Toshiba is using a Marvell Controller for is PCIe SSD drives that I've seen. Good Luck, and OPEN HER UP!
My 2013 MBA 11" I bought yesterday has a 128GB Toshiba.