If he looks completely fine, acts completely fine, eats completely fine, does everything completely fine, bar the once-in-a-while flashes, then it could be nothing. It's like humans. We scratch our bodies from time to time, doesn't mean that we're about to die. XD
That said, do keep an eye on him. How often are the flashes. If he doing it to the bottom of the tank, or surface he can see? Cichlids generally have certain behaviors that utilizes 'flashing'. Many communicate by seemingly spasming. I know a fish down with ich or the likes will scratch themselves on any surface possible, especially rocks and driftwood and all that.
So yeah, keep an eye on him.