WordPress SEO was updated to version 1.4.22, from version 1.4.21. Changelog:
- Reverted change to XML sitemaps stylesheet URL as that was giving issues on multisite installs.
- Reverted change to XML sitemap loading as we were no longer exposing some variables that other plugins relied upon.
- Fix bug with author sitemap showing for everyone.
- No longer save empty meta post variables, issue #463. Clean up of DB is coming in future release, if you want to clean your DB now, see that issue for SQL queries.