Birth control pills as well as other medicines like cimetidine
or antidepressants can result in nipple discharge
.however there may be other reasons for it like
Rubbing on the area from a bra or t-shirt
to the breast
Non-cancerous brain tumors
Small growth in the breast that is usually not cancer (intraductal papilloma
(underactive thyroid gland)
Fibrocystic breast (normal lumpiness in the breast ) etc.
It is abnormal if it comes from one nipple or it flows of its own or if it bloody.
Yours look normal and seems to have been due to use of birth control pills however to be on safer side,you may consult your doctor and get yourself examined.