If the spots are not uniform in size/shape and don't "migrate" around the body, no, not a problem. Have you added any new corals/frogspawn/mushrooms as of late? This blackening is a melanistic responce to the fish trying to host in something new. They will go away as the fish becomes adjusted to the "host".
If the are uniform and seem to move around the body, it could be "Black Ich". And that is a problem. Do a search. A FW Dip can help drop them off and also be a test to ID that it is Black Ich.