I know you asked a question about possible pregnancy earlier.
It is not really normal if you are experiencing the discharge without any stimulation and if you are not pregnant. Sometimes the discharge could be nothing special but there could be serious causes as well.
It depends on if the discharge is coming from one or both breasts, if you have redness or tenderness around nipples or some kind of lumps. It could be an infection, a cyst or a benign tumor within breast ducts. These could also be high levels of hormon prolactin (active when pregnant). If you are not pregnant and have high prolactin levels, there could be another reason behind these high levels that should be investigated.
I would certainly make an appointment with your physician.
Keep us posted.