@nate Hmm, can't really say for sure, as I haven't used BS for a long time.
But, reading http://getbootstrap.com/components/#glyphicons-how-to-use tells me that those fonts should be included in the Bootstrap CSS and loaded via @font-face. And that it tries to find & load those fonts from the ../fonts/ directory, relative to the compiled css file.
So, if you compile your CSS to /css/dist/site.css, it'll try to find those fonts from the /css/fonts directory. Thus that path.
And that extra slash shouldn't make any difference.