It was recently brought to my attention the BNS Inline Asides plugin was not working correctly under a particular set of conditions.
This is a really cool plugin. I installed it on my test server which uses a separate domain for plugins. This is causing the stylesheets to not be included.
Which gave me the nudge I needed to properly enqueue the stylesheets the plugin uses. Thanks to Michael Fields and his bug report; the plugin went through two quick iterations and the issue was resolved.