[Plugin: WordPress SEO by Yoast] Facebook thumbnail only working on newer posts?

Hey all,

I’m having a head scratcher where the Facebook thumbnail is working on my newer posts such as this one:

http://foodintegritynow.org/2012/04/12/austin-vickers-people-v-the-state-of-illusion/

But not working on my older posts such as this one:

http://foodintegritynow.org/2010/09/30/food-integrity-now-e15-amy-kalafa-of-two-angry-moms/

I checked out the meta tags and everything looks the same. Anyone have any ideas why this may be?

Thanks,
Matt

http://wordpress.org/extend/plugins/wordpress-seo/