Earlier ReCaptcha add-one has been working, but now it seem to identify use

Earlier ReCaptcha add-one has been working, but now it seem to identify user as human automatically. This seem to happen even with oneline demo. I got following warning from Google Analytics: “We detected that your site is verifying reCAPTCHA passed solutions less than 50% of the time. This could indicate a problem with your integration with reCAPTCHA. Please see our developer site for more information.”
Could someone do bug fix for ReCaptcha add-one?