The stuff between "---" in the headers is not getting rendered - only horizontal lines are created

Why does this occur? Does this automatically convert the stuff into some kind of meta-data? Example below:

---
layout: post    
title: Just another post
something: more
this
and that
and more of that

---

About Me
--------
I'm a programmer 

Output is like:

<hr/><hr/>About Me<h1>I'm a programmer....

The stuff between the first two hrs is missing for some reason I do not understand. Is it considered as document metadata?

I've also posted the same question on stackoverflow:
http://stackoverflow.com/questions/18007857/markdown-rendered-incorrectly-with-npm-markdown