Did you know - WordPress plugin SEO Ultimate's open Graph Integrator causes a warning?
This is a bug in the SEO Ultimate plugin. You should report that they are incorrectly calling:

apply_filters( 'single_post_title', $post-&gt;post_title )

in three places:


modules/opengraph/opengraph.php (line 116)
modules/titles/titles.php (line 179)
modules/titles/titles.php (line 184)


The call should read:

apply_filters( 'single_post_title', $post-&gt;post_title, $post ). 

Their support page is here:
https://wordpress.org/support/plugin/seo-ultimate