Still Breast Feeding?

Gwen Stefani is still breast feeding Kingston and he is one and a half years old. Isn't that a bit odd? She recently said this in a interview:

“I don’t know when I’m going to stop breastfeeding. I’ll just keep going while I can - like, he’s getting his teeth so it is a little bit scary. He’s bitten me a few times!”
-Gwen said from her hotel suite during an interview in London