Cisco Web Security proxies and Captcha

I've got a bunch of users at my office who were being prompted for Captcha responses when trying to do Google searches starting May 1. Cisco is claiming Google changed something at that point. Is there any way to get more details as to what might have changed (if anything)? -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://bit.ly/1dkFnYd. For more options, visit http://bit.ly/P65DvS.