Have you edited any Graphene theme files or WordPress files? It doesn’t appear that this was entered using any of Graphene’s options. If so, try a clean install of Graphene.
Try temporarily switching to the default 2011 theme to see if the problem persists.
You should also try disabling all your plugins temporarily to see if one of those is causing an issue:
http://blog.kjodle.net/2012/06/15/disable-your-wordpress-plugins/