When I masturbate, I find flakes on my fingers, it is from my wet vagina that gets dry in a couple of minutes. What could this be?

Dry mucous. The liquid which luricates your vagina is produced by bartholin glands. It is mucoid in nature, which makes vagina slippery in anticipation of receiving the male organ.This material when it is dry , it is flaky. Nothing to worry about, it just means you have healthy vagina capable of producing normal lubrication.