I'm not a behavior scientist..but it's fun to theorize
My daughter was a headbanger when she was a around 1 yr. old:headbang2:, to put herself to sleep when she was a baby. It is probably totally unrelated, but if there would be any similarities in behavior, the doctor said it was to calm herself, as she was highly stimulated, and it took alot to calm her down, so the banging helped her to focus on keeping her brain free from all thought , in order to relax. Another way to look at it, is that your fish could be really bored, and looking for something to do... My dog has destructive behavior when he is bored... digging holes in the yard, sending dirt all over the place...:dog:
I don't have a wrasse, but he sounds like a lively, interesting guy. Does he pick on any of the other fish? I'd rather have a fish do what urs does than aggressively bang into another fish, as I have happening between a yellow tang and a Naso tang.