Thank you for asking. I can understand your concern. Well, a slight curvature of penis shaft can be normal. If one is able to have intercourse, if there is no problem while urinating, if the curvature is not worsening, etc then it can be considered as normal. It would be a problem if it causes impairment in the functions of penis. If there no such difficulty, then there is no reason to be worried. Scar tissue often is the cause for such a curvature. Subtle injures, trauma during the developmental phase can result in such an issue. Very rarely it is pathogenic or a disease.