Ans: Don't worry, this is not mold, these white substances developed during the soap saponification, it is the reaction when soap met with the air during saponification. This soap is still good to use. They will go away when you wash the soap with water or shave them away.
Q2. How do I know if my soap is soap still good to use?
Ans: No bad spot (dark color as shown in the photo) and no uneasy smell. I believe everyone know how to differentiate good and uneasy smell :) Handmade soap can keep up to 2 years if you know how to store it. Keep it away from moist and in good ventilation area.