On bcp, bled brown blood one day during time of period. been on bcp over a year. normal?

Yes: Because the birth control pills on the market today are contain a low dose of estrogen compared to the progesterone, there is little to make the uterine lining grow so over time there becomes less lining to slough off with a period and periods tend to become shorter and lighter. This is considered to be a non-contraceptive benefit of the pill. Hope this helps.