If you just made these this past Sept I am guessing it is not DOS, but possibly fragrance oil. I find DOS and rancidity seem to be a different animal. I have had orange spots that were not sticky or off-smelling (rancid) than I blamed on the fragrance oil. On the other hand, I have some Patchouli soaps that are just showing some rancid areas that are off-smelling and sticky but they are at least 4 yrs old and the rancid area is on the outside edge of the soap which I cut off and still use the soap. The rancid cut-off part smelled off.
If your shea is natural, not bleached shea that would answer the nutty fragrance which may have overpowered the fragrance you used. I have had shea which I purchased from a destash that I know was several years old with no rancid issues. I normally purchased raw shea in 25 lb blocks 2 at a time and stored it for 2 yrs+ with no issues.
I use chelators, EDTA with Sodium Gluconate at 0.5% each in all soaps, which I will probably try upping a little when I move next year unless we get an RO system up and running on the extremely hard well water we will have.