Not sure if I am having a conflict with WordPress SEO or another plugin. But started on the last few versions of WP SEO when I checked my sitemap.xml instead of a sitemap it showed the Robots.txt. Strange. So the only way that I could correct this was to install Google XML Sitemaps by Arne Brachhold. I also deactivated the Robots.txt plugin and added the Robots.txt manually just to make sure that it wasn't a problem with this plugin.
Sometimes I can edit the Robots.txt file in WP SEO and sometimes it doesn't show up. Don't know why it is inconsistent on my sites.
Anyway if you haven't checked your sitemap.xml lately since you installed WP SEO you might check it just to make sure that it is okay. It certainly might just be my install or some plugin conflict and I do not know if it is related to WP SEO. I am using Genesis with Child Themes and my standard plugins.
Making the changes noted above corrects my Sitemap.xml. Anyone else having this problem?