What Causes Light Brown Discharge After Coming Off From Loestrin?

Hello, ive been taking loestrin 20 now for 11 months, and i have been fine getting only a few mild side-effects when i first started taking them. Since then the side effects died down. However, this time for my withdrawal bleed, it hasnt been like a period, its just a very light brown discharge. In the last two months ive had the 1st and 2nd hpv vaccine, that may have something to do with it but im not sure. Can you help?