I spit on my penis while masterbating, later that evening i felt a cold sore coming on. will i get the infection on my penis now?

Little or no risk: Self-infection of a new area of the body with herpes (auto-inoculation) is rare. Once someone has had herpes for more than a few months, the immune system prevents new infections with the same HSV type. To be maximally safe, try to avoid similar events in the future. But probably no harm will come this time or if you make the same mistake again someday.