I used one of the saliva microscopes too and had intermittent light ferning. I found that I had to put a big thick blob on it and help it dry with a hairdryer (it would take forever otherwise) to get a ferning or pebble pattern.

Things don't always work the same as it has done before when you come off the pill. Just when you thnk you know your body it goes and does a new trick to keep you on your toes