Mitch on "[Plugin: FunCaptcha - game CAPTCHA] Warning: Couldn't retrieve challenge url"

I have Version 1.1.0 of FunCaptcha and I noticed this in the error_log in a few sites
[20-Jan-2014 13:33:40 UTC] Warning: Couldn't retrieve challenge url.
[20-Jan-2014 13:33:40 UTC] Warning: Couldn't retrieve session.

what is causing this

http://wordpress.org/plugins/funcaptcha/