If it was melt & pour you MUST spray the dry layer heavily with rubbing alcohol & pour the second layer quickly BEFORE before the alcohol evaporates. This is true anytime you want to make layers, insert soap chunks or even toys into the soap base. It acts as a glue kinda sorts....
Nope, it was not a melt & pour... We mixed lard/lye and cooked the soap... But when we poured it, it separated into 2 layers with some oil in the boundary. The ambient temp was 96*F when we poured, and we did not want layers at all...
Was this a CP or HP soap? I know you said you cooked the soap but I am just wanting to make sure. Did you use milk or honey in the recipe? How accurate were your weights? If CP, your mixture might have gotten too hot and separated. Or you could have got a false trace. If HP, perhaps your soap didn't fully saponify during the cook. I don't do HP so that is just a guess.
You can grate it down and rebatch and see how it comes out.