Any others experienced crashes when quitting a game that was startet from your home screen? Most likely a Safari bug - I've had the same problem on iPod 5 and iPad 2 and 3 - they freez totally and doesn't respond to anything. A reboot is the only option. It happens quite often, but I never if you enter the game via Safari directly (typing the address) (!)
Here's one of my games that produces the crash, try adding it to your iPad/iPod/iPhone home screen, start it from there, and then quit it by pressing the iPhone home button.
Sorry for not following the guide on how to report bugs, for now I just want to know if others have had similar problems. If so I will dive into the problem and try to reproduce it with a smaller file.