That is called ‘time for a vet visit’. I’m not sure if it’s a papilloma. I think it’s probably a scab or similar which is coming from a case of stomatitis (aka mouth rot). Best to have it checked and treated asap, as left untreated the infection can make its way down into the bone. Attaching our vet list in case you need help finding one with chameleon experience, although most exotics vets should be able to handle this.