You should never ignore any lumps or masses on your pet, even those that look unremarkable or are not bothering your pet can turn sinister very quickly. Your vet can offer diagnostics to determine if your pets lump is anything to be concerned about.
If you notice a lump that isn’t bleeding, infected, or seriously bothering your dog, it can usually wait until normal business hours. A small amount of bleeding can be treated by applying pressure to the area for several minutes. Cleaning other lumps with dilute betadine and monitoring may save a trip to emergency also.