Just make sure your cell phone or electronics are larger than the filler hole on the gas tank! Never know when a perfectly dropped item goes 'splash'. Stranger things have happened. Just ask my buddy when I worked in another city and we were leaving work. He was running late and pulled out his keys as we went to step into the elevator and....need I tell you the rest? Yep. Dropped the keys and they disappear into the crack between the elevator and the floor. He missed his appointment, but enjoyed a tour of the bowels of the building where, 34 stories below, he and the maintenance man found his keys (and several other unmentionable things) in the pit below the elevator shaft.
By the way:
Urban Legend - cell phone set off gas station blaze
http://www.snopes.com/autos/hazards/gasvapor.asp
Also busted as false on not one, but two episodes of Mythbusters:
http://mythbustersresults.com/episode2