I got a fever blister inside my mouth 10 days ago. it has since gone down & healed, but i was wondering if i'm contagious?

Herpes simplex: Herpes simplex is a virus that you catch from someone who is infected with it. Most transmission occurs when persons shed virus but lack lesions. Usually skin-skin, skin-mucosa contact. Hsv is inactivated promptly at room temperature. Aerosol or fomitic spread unlikely. Infection occurs via inoculation onto susceptible mucosal surface or break in skin.

Not contagious: If it is completely healed you need not worry.