I don't know, but I do know that driving can be intensley triggering. (I'm not allowed to drive.) You say there were no triggers, but was it a stressful driving situation? I hallucinate accidents, and have tasted blood. (On trains, in cars, either driving or as a passenger.) It could be that subconsciously you were worried about an aspect of the situation, and you found it hard to confront that anxiety consciously. (Good Lord, I sound like such a psychobabbler...) Anyway, the thing is, even neurotypical people have hallucinations, or random anxieties. It's not well advertised, but it's true. Just because you had one blip, it doesn't mean that the full on crazies are about to make a comeback tour. Don't panic.