I started getting this warning message when viewing any page on my site, only when not logged in. It started happening when I chose not to display any header image. It shows up at the top of the page.
Warning: Invalid argument supplied for foreach() in /home/content/82/5061382/html/wp/wp-content/plugins/styles/classes/styles-customize.php on line 155
I'm using WP 3.6, Twenty Thirteen Version 1.0, Styles Version 1.0.9, Styles TwentyThirteen Version 1.0.3.
For now, I deactivated the Styles plugins.