cabrzama on "[Plugin: Wordfence Security] Critical Problem with Core File"

Hello, on Friday I installed a plugin called Wordfence Security to help protect my site that I just barely finished building. Upon initial scan Wordfence spotted what it calls a "Critical Problem" with a core WordPress file so I wanted to see if this was something you all think I should ignore or if it really does look like someone has hacked my site.

Here's what the error says:
WordPress core file modified: wp-admin/setup-config.php

I have a screen shot I can show you of the difference, here's the
difference of what Wordfence says it should be and what it is:

Should be:
Line 263 if ( ! is_writable(ABSPATH) ) :

what it is:
Line 263 if ( ! win_is_writable(ABSPATH) ) :

http://wordpress.org/plugins/wordfence/