I am pregnant with #4, and I have never experienced leaking while pregnant. I don 't think you have anything to worry about.
Yea it's pretty normal. It can happen at anytime. With my son I noticed it at 16 weeks. This time around I didn't notice it until 24 or 25 weeks maybe. And it was just a tiny bit at that, even now and seems different this time around. Once you have the baby, you will have more and then start producing milk a few days after. I wouldn't worry about it.