XDJ-XZ Freeze

Hello, I had read here somewhere about freezes before. Never had one until yesterday. I cannot completely replicate it. But i was using 2 channel standalone mode with a 128gb usb stick. As the days before also. I played with the ping pong echo. And suddenly no control inputs where accepted anymore. Track kept playing but could not browse. Nudge, scratch, fade in and out... Nothing... Switched it off and back on and it was back to normal. Seems i caused a hickup in the firmware somehow. The session was shorter than the ones before in the same envoirment so i rule out these as influence. Pleas have a look for a flaw in the firmware. I will report if it should happen again