I do not think it is.
Gliders chew foods and suck out all the juicy parts then neatly spit out little moon shaped pieces of the solids. It looks like your glider has done just that but spit it back into the food dish where the 'spitlings' absorbed moisture from the remaining food.
The brown stuff looks a lot like cheerios do if one is left in the empty bowl - where it shrinks to a circle about 3/8 inch and dries dark brown.