Lighter than normal period (was on a few flights during this week) and 14 days later some ovulation bleeding. could this be due to the light period or something else? on birth control

It happens sometimes: Many women have occasional variation of their mucus discharge, some spotting between periods, a heavier or lighter period, a different shade of color in the menstrual blood, a longer or shorter 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 doctor is a good idea if symptoms are persistent or worrisome.