Hi, Ive been making cp soap for over a year now and prefer to use essential oils if Ican, however a couple of my citrus bars seem to develop a rancid smell after curing (it usually develops in about week 7 or 8 of the cure). It seems to mostly happen in any bar with Lemon or Bergamot in it. There is no obvious DOS on the bars and I have purposely formulated them to avoid it as I live in an area with high humidity. All my other soaps seem to be fine. Has anyone else has come across this problem? I've googled it extensively but I couldn't find anything.