Is this normal?

I was looking at my nipple because I noticed some liquid in it and I was checking to see what it was and I squeezed to see if it was coming out of my nipple or if maybe it was just water from the shower but no it's milk coming out of my nipple.. I just got off my period and it was normal. I don't know is this normal if you aren't pregnant or have a child because I don't have a child and I've never been pregnant and I thought that was the only way you produced milk.