Hi, could be.....
Excess/undisolved lye? Check you numbers. Have you zap test yet?
Stearic spots? What temps you working at? Maybe soap a little warmer?
Ingredients? What is in it?
How thick a trace did you pour at?
It could be many things. But these seem to be, the most common. My guess is temps and trace. Please let us know how you make out.