First iOS 7 bug that I found

So yesterday I was talking to my brother while taking a walk along Lake Union and something strange happened.I heard some tones. My ear dialed "4" a few times. It's odd since the face sensor should have turned off the display. Not only that but I had the phone locked.A half hour into the call it came to a close and I found this on the screen.Eh?I googled a bit and that's what you get when you try to unlock the phone with the wrong passcode. I didn't even try that -- oh and I have the fingerprint sensor as well.I walked back to the office without the podcast I was expecting to be playing.I took the above screen shot though.When I was five minutes from the office it started working again. Odd. I have no idea what happened. I do know it was quite annoying.Has anyone else seen this before?