I've always had normal cycles, 20th of every month, normal for the month of december but 6th of january spot for 2 days 15 days apart is that normal?

A one-time symptom? Many women have occasional variation of their mucus discharge, some spotting between periods, a heavier period, a lighter period, or even a missed period. Having one or two of these symptoms doesn’t necessarily mean there is a medical problem, but a visit to one’s primary care or ob-gyn doctor is a good idea if symptoms are persistent, recurring, or worrisome.