Looks very much like one. A better shot in white light and with a magnifying glass would help ID it with certainty. Watch it carefully and not what it is feeding on. They are well-known polyp munchers.
Sorry about the pic; I had to take it quickly, as the silly thing emerged when I piped in some Reef Roids at the acans. I dipped the entire frag in Coral Rx, which made the acans pout, but the worm hasn't reemerged. The worm is half red, and half brown, and was nosing around delicately in the oolite, but went back into a hole in the frag when disturbed.