My OS puts hard spaces after #'s

My OS puts hard spaces after #'s

I'm having a small issue when writing Markdown documents because for some
reason OS X adds hard spaces after the character #. If I type this:
## Title
I would expect to get this:
<h2>Title</h2>
But because my system puts a hard space after the last #, I get this:
<h2> Title</h2>
I'm saying my system because I've had the issue with two different text
editors. I have no idea where I could fix this. Currently I'm working with
Vim and I'd welcome an editor-based fix as well!