Dandruff appears when our scalp becomes overly oily or dirty, and the yeast on the skin is so well-fed that it starts to flare up. It is probable that the natural oil of your hands is adding to your natural scalp ecosystem and making it more oily than usual, hence the dandruff flare-up. Dandruff is ultimately an issue of scalp imbalance. You can try a scalp massager or do your massages right before washing your hair and see if it helps! We teach in detail how to find the right amount of 'clean scalp' in the Shampoo module of the Haircare Lab, plus tons of other ways to boost your hair growth and retention. You can check it out here: http://hairqare.co/get-better-hair