iPhone 5 non-responsive when ringing I have an iPhone 5 with iOS 6.1.4. No third-party software like apps are installed --- the device is all but fresh from the factory. 

The device gets non-responsive sometimes when I get an incoming call (about one call in 20) -- the phone keeps ringing but it's impossible to answer it because the touch screen won't respond. After clicking the lock button (on top of the device) a few times, the call is lost and the device gets back to normal, which makes me think this is an iOS bug and not a hardware problem. 

Is there any workaround for this problem?

Edit: After using the phone more, I've noticed that the UI may suffer hiccups in many more situations (for instance when texting somebody a message); the phone freezes and becomes unresponsive for a few seconds. This behavior is obviously most annoying when you can't answer incoming calls.
I couldn't ring out or accept incoming calls on new Iphone 5 as it had become unresponsive, there are very few apps installed on phone as it is new. Turned power off and back on and phone works again. Hope problem is not recurring.