Furminators are not the best grooming tool to be using on a rabbit. Rabbits have very delicate skin and furminators can easily tear a rabbits skin if extreme caution isn't taken in using it. This isn't the first incident of one of these causing a skin tear to a rabbit, that I have heard of. If there is not a deep wound that needs stitches, then you will just need to keep a close eye on the patch of skin to make sure it doesn't get infected if there is any broken skin that could be considered a wound. If you want to put a light film of neosporin ointment(plain, no added pain relief or other additives) over the wound, that may help to aid in healing and preventing infection, as long as your bun doesn't just immediately try and groom it off, otherwise it wouldn't really do any good.
I would also suggest not using the furminator on your bun anymore, and instead use something more gentle. I've found just using a dampened hand, to work the best at removing loose fur.
