I have had the same thing, both prior to ever getting pregnant and post children. The doc originally found it when doing a breast exam. The fluid is called collostrum (spelling?) and is the pre-milk a woman has just after childbirth prior to her milk coming in (it is highly nutritious for a newborn). I still can extract it from myself now, and my last child stopped breast feeding 4 1/2 years ago.

Just to be safe you should mention it to the doctor, but don't stress out too much.