Agreed, looks like damage. I'd monitor, and if it gets worse, remove it. Use a clean, sharp pair of scissors and cut just above the damage line. It's not too scary--fins are pretty durable, and in clean water should heal promptly. You just want to remove necrotic tissue.
Scary for the snipper, not so much for the fish. Fins are pretty robust--biologists will 'clip' a fin in order to mark fish in the wild with a hole punch. It's done when a wild population is manually spawned to raise the eggs in a hatchery--this keeps them from spawning the same fish multiple times in a single season. By the next year, the marked area has healed completely.