Buck warts (cutaneous fibromas) as it is commonly called. He should be fine and believe it or not the meat is fit to eat (as long as there is no bacterial infection of the fibromas). It is a virus that usually lasts about 2 months. They won't cause any real harm to the deer unless they are very close to the wind pipe or esophagus (or other places which may interrupt breathing or feeding). There is also a risk for bacterial infection which in that case would cause the meat to be unusable. The disease cannot be transmitted to humans (As far as we know) and is most commonly transmitted by insects.