Why my iPad mini has been frozen?

I know how to resolve this, it just need reboot but I would like to know if its a common problem.

Just a few days ago the display shows the correct time, but I cannot "slide to unlock". Even I cannot enter the password because the numeric keypad doesn't appear there, I can receive notifications and I can use Siri but I cannot open apps, even if I wanna open the camera it doesn't answer, I can't.

Is this common? Or if the problem continue even if I can resolve it by my own, is better if I go to a Apple Center for technical support? My guarantee has not lapsed yet.