iPhone 5 with iOS 7 randomly shuts off

Are any of you aware of iOS 7 randomly shutting down iPhones? Ever since I upgraded 2 day ago it has shut down at least 3 times. The battery was at about 18%, 20%, and 36% when it shut down. I don't believe it’s a bug with the battery percentage because it started back up as soon as hit the power button. Also, it is not due to overheating or anything else wrong with the environment. Nothing in the environment has changed except that I updated to iOS 7. Let me know if this occurs to anyone else and if there are any solutions pending?