Ok so I'm 4-5 days in to my new 64gb iPhone 5S and have noticed it keeps restarting itself. On several occasions I have been using it and the screen suddenly turns blue then black then on to apple logo. I have searched the web and have seen a thread on Apple forums about it. Some people say it's a hardware problem and phones need to be replaced. However some people are saying they are experiencing same problem on iPhone 4S and 5 after upgrading to ios7. Closest Apple store is out of town and unlikely to have any iphone 5S's in. Don't want to replace phone if it's just a software bug. So thought I would start a topic on here to see if anyone else is experiencing the same problem?