reCAPTCHA Keys expiring?

Hello, We've added reCAPTCHA to a Visualforce page used on a Salesforce Force.com Site. Recently the reCAPTCHA stopped working and we were able to correct the issue by generating new Public and Private keys. My question is to reCAPTCHA keys expire? Cheers, Chris -- 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.