If it’s just happened the once, & it cleared itself by switching off the ignition, I wouldn’t worry. The ECUs are programmed so that if there’s a misfire, or similar, it will switch to “safe/limp mode”, thus 2nd cam will not come on. I appreciate that you probably won’t have had a misfire, nor owt else wrong, but all ECUs are very susceptible to a spike in the power supply etc. I’m sure it will have been just an unexplainable event, which will probably never happen again. (Cars & women, eh, I’ll never understand some of their behaviour )