Any new bumps that appear anywhere on your body should be a cause for alarm for any person, and it is always necessary to visit a physician to have them reviewed. The fact that you are a non-smoker is a good thing, as smoking obviously has been found to cause many cancers, including cancers of the mouth. Even so, you need to have the bump looked at by a qualified physician, either your primary care doctor
or a specialist such as an Ear-Nose-and Throat surgeon
). It is even more important to do this soon if you have had any other concerning symptoms, such as recent weight loss, bleeding from the lesion, masses in other parts of your head and neck, etc.
Now that you have promised to see a physician, there are some things that are completely common and benign, and quite possibly explain what you have noticed. One of these is torus palatini, which are firm growths that come from your hard palate (the bony plate at the top of your mouth), and are painless. These bumps can also appear in other bones of the head and neck (such as your jaw). While these could quite possibly be what you have, please see a physician who can confirm that you do not have something more serious, possibly including cancer.