It depends, they usually stay but don't cause any real problem. If it's a slight calcium deficiency then just be sure he's getting enough calcium and proper lighting. There's a very slight chance that it could be related to the end tail rot.....I doubt that it is but that may be the case if the infection was spreading up under the skin. But again, I doubt it's that, just a slight harmless bump. If he's getting proper calcium + uvb he should be O.K