printer icon broken image

The printer icon appears as a broken image:
you can see it in this post:
http://www.livinggreenwithbaby.com/recycle-idea-new-desk-using-old-closet-doors/
(bottom right below post)

This just started happening.
I updated the plugin t the most recent version then checked and it appeared fine. I also just updated my theme and Woo framework (I believe it was fine after that). I also just updated wp to 3.6, could that have caused it?

I have it set via the settings page set via radio button to post and pages rather than code or shortcode.
Any clues?
thanks
Michelle

http://wordpress.org/plugins/printfriendly/