Honestly, it could be that they were grains of sand stuck on the fish due to the mucous coating.
Also, a flasher species is the last fish I’d expect to see get ich, in fact even the hardest of wrasses tend to get ich and other diseases last.
What I first thought based off of it being a wrasse.
I'd just watch for a few days and see if any other fish start to show signs. If they do it's either one of those things where you try to reduce stress and feed well to live with it, or let the tank sit fallow and treat everything.