Fish Rubbing on Rock, Flukes?

[SuperSaiyanTang]

I was watching my tank over the past couple days and every once in awhile my Flame and Melanurus Wrasse will rub against the rock. This isn't regular but they do seem to do it some times. All of my fish in the tank are eating and seem happy. I dont see anything visible on the outside of the fish. The only thing I could think of that would cause it would maybe be Flukes? I unfortunately did not QT my fish. At this point Im trying to get ahead of the curve and stop anything from getting worse. Here are some pictures of the wrasses.