If the bump is flesh colored and over a vein, it can be just a
varicose vein (especially if you have
varicose veins on other places on your body). Age is not a factor, from teens to older adults can get varicose veins on the penis or scrotum (and other places).
These type of varicose veins can range in size with most the size of a BB or smaller (or bigger). Inspect it closely. If it seems to follow or be "on top" of a vein, this is probably what you have.