I have just a little nipple discharge when squeezed. Could it be dangerous?

Depends. What color is the discharge. Bloody or rust colored nipple discharge could represent cancer. The nipple can leak fluid of many different colors and could be benign. See your doctor!
Normal. It is normal for a woman to be able to express small quantities of clear or white fluid from the breast. That would be normal. A discolored or bloody discharge should be evaluated by your physician.