Yoast/wordpress-seo — pull request #171 by mbijon (2013-08-14 05:48:33+00:00)
Title: PHP Notice logged when site has capabilities created without 3rd value in args array

Check if offset [3] exists in capabilitites array before confirming value of the 3rd arg.

This only seems to occur when using a client's custom capability manager plugin. I have edited that plugin too, but this seems like a good defensive fix w/ no negative outcome to checking if capability is specific to the SEO plugin