OK DAMNsels have been removed!!!

I have since bought a really nice, calm cool lunar wrasse that everywhere I checked was ok and LFS told me ok. (they know what I have) well tonight I brought home a mandarin- and the moment he went into the tank the lunar started to 'peck' at the mandarin? He hasn't bothered anything else. Not the fish, not the coral, not the shrimp or crabs, nothing- why the mandarin? Do I need to bring him back? What's the deal?
