I had a very similar issue with my P12 almost two years ago. It happened when I changed patches fast and it affected just two voices, so there was some kind of issue with one of the Shark processors or similar, as each processor seems to handle two voices/leds. In my unit it made even stranger digital glitches.
Got a new board and sounds great. Don't worry, it will be fixed fast by the great people at DSI. Exchaning the board is very very easy.