been doing some googling and thyme might be the culprit. from brambleberry product review of white thyme oil:
I'm so glad you loved the way the White Thyme Essential oil smells! Though I' sorry you were disappointed in how it behaved in Cold Process Soap. We decided to do some more testing of this essential because of your reviews and found it does accelerate! To help slow this down, take 1 oz. (basically equal amounts of fragrance oil to fixed oil) liquid oil out of your recipe and heat it up to 100 degrees. Then, add your fragrance into this oil. This simply dilutes the fragrance oil’s initial acceleration. You can also add the oil/fragrance mixture earlier than usual. Rather than adding the fragrance at a thick trace, you can add it at the first sign of thin trace. Always hand stir the fragrance/oil mixture in with a fork/ladle and never, ever use a hand blender for problem oils. Lastly, raise your temperatures to about 110 to 115 degrees. This will help to keep your mixture more liquid than at a lower temperature.