Have the same issue, it's definitely a software issue. When it happens to me, which is often, this fixes it every time:
1) Have the app misbehaving open
2) Hold the power button down until the slide to power down slide shows up. Let go of the power button.
3) With that slide showing, hold down the home button until the screen flickers and the app closes. Now re-open the app and the gyro will be working again.