Why are my venison ribs waxy?

I just simmered some venison ribs in the crock pot for 10 hours and the first 5 or 6 were phenom. As they started to cool, and I continued eating them, I noticed a waxy fat was starting to coat my mouth. It doesn't have a bad taste just an unpleasant feeling. Is it from the fat beginning to cool or are some parts of the ribs better left for the grinder? Thank you