I don't think it's a hardware issue, because my iPhone 5s also crashed yesterday when I got off of work and went to listen to iTunes Radio when I got in my truck. I clicked the music app (which had my radio station still opened) and it was unresponsive. Minimized and clicked on it again a couple times only to see my screen go black and then show the apple in the center as it was doing a quick reboot (didn't take nearly as long as a full reboot...only about 3 seconds or so). All has been fine since. This has happened once or twice before as well since I got my 5s. Hopefully Apple will come up with an update to improve the stability sometime soon, because I love me some iTunes Radio. lol