SSL Issues -> Ultimate Facebook

I am using the Facepile widget, I get this through a test of why my page is not completely secure:

Domain Name: iphonehax.net

URL Tested: https://iphonehax.net

Number of items downloaded on page: 231

Valid Certificate found.

Certificate valid through: Aug 15 18:43:14 2013 GMT

Certificate Issuer: Starfield Technol

Total number of items: 231

Number of insecure items: 1

Insecure URL: http://www.facebook.com/plugins/facepile.php?href=https://www.facebook.com/pages/iPhone-Hax/408754029187463&width=300&locale=en_US&max_rows=1

Found in: https://iphonehax.net/

Secure calls made to other websites:

fonts.googleapis.com is valid and secure.

connect.facebook.net is valid and secure.

themes.googleusercontent.com is valid and secure.

s-static.ak.facebook.com is valid and secure.