Agree with all safety precautions when fueling. Cell phones are no longer prohibited because they to not give off an open spark that is nearly enough to ignite fuel in the most optimal circumstances. No one has been able to provide any evidence of a cell phone causing a fire at a gas station or fueling area. There have been countless tests in controlled environments with all styles of phones trying to ignite fuel vapors, it just doesn't happen.
What was once attributed to cell phones has been determined to be static shock. People would start fueling, get in their vehicles to talk on their phones, exit the vehicle with phone to ear, not grounding themselves on the side of the vehicle. As soon as they touched the nozzle, spark and flame ensued.
Safety Note: do not re-enter your vehicle when fueling. If you do re-enter, ground yourself on the door frame or metal bollard at the gas pump prior to touching gas nozzle.