Very strange, I never have it go pink immediately, or if it sits for a few days then it turns a hint of pink. I just processed some yesterday and it is still a pretty light green. I wonder if you processed the resinous latex goop that will run to the bottom, I do know it will add to the color changing. Since you purchased your leaf I would assume it is the same I use and I have purchased the large leaves when I have none to cut. The larger the leaf the more they need to stand up and let the resin run to the bottom