Thanks all for the advice. Went to dealer this morning and it worked after a few tries. So I left the dealer and went to gas station. Didn't work - then it occurred to me this was likely a software problem since I never heard the mechanical release sound when I would push the button. But I had tried all permutations of powering car down, putting car in ACC mode, Stealth, Sport, off etc. and it still didn't work before. So before I went back to the dealer I remembered all the issues people had with USB accessories etc. I have a car adapter for my iPhone 5 that is plugged into the 12V in the arm rest. So I unplugged it, let car go to sleep, and turned car back on and hit gas button - and it worked! Haven't tested this again but I will later today. Wouldn't have thought that the 12V power plug would have any effect on the gas cap release but looks like it does. Will try it a few more times later today to see if that is the culprit!