You have until July 11, 2017 to see if you have unclaimed property with FasTrak.
Here's a brief explanation from fastrakunclaimedproperty.org:
FasTrak is looking for the owners of uncashed refund checks to provide them with an opportunity for repayment. If valid claims for repayment are not received, the refunds will become the property of the Bay Area Toll Authority (BATA) through a process called escheatment (California Government Code Sections 50050-50056).
I'm no lawyer, but giving your money to the Bay Area Toll Authority is something I'm guessing you don't want to do.
It's super easy to search for your name. Just CLICK HERE.