Anything is possible, especially if you did not have the problem prior to having your timing belt replaced. Coincidence maybe. When replacing the timing belt they do have to remove the upper radiator support. In doing so, they may have inadvertently disconnected or damaged the radiator fans connector or wiring, or the fan just simply failed. Since I cannot inspect the vehicle, you can always get a 2nd opinion and If you choose to have them replace the fan assembly, ask them not to discard the old parts, but to put any parts replaced in your vehicle. You may have them checked by another party at a later time.