Apple watch randomly types in incorrect pass code

My Apple watch began running the stopwatch randomly. When I tried to intervene to turn the stopwatch off it asked for my pass code. While entering the four digit code an incorrect code was entered at the same time (I could see the wrong numbers as they were entered). After several tries I was locked out...first for one minute, then five and now 15 minutes. What is going on? How can I stop/correct this?