This is little wierd, but i could see a 'red cross' just next to the pages i have created under site pages when i open them in sharepoint designer, what is more surprising is that only home page does not have this symbol except that all pages have
a red cross next to them.
From the screenshot you posted, I cannot reproduce the issue in my environment. Please provide more information about how it occurred. Did you perform the action on a SharePoint server or client server? Did you have full control rights to this web application
and access to SQL server?
You could try on different machines using different accounts and see if issue still occurs.