Oh, and this should not have the INFO level in my opinion. Other log lines indicating a problem with the master (such as a time out or unreachable host) are not flagged as INFO.
Maybe you could file a Jira ticket? Don't forget to specifiy your Solr version. Also, please check the master log file if there something funny around the time the slave throws this error. > Since they are not flagged as errors or warnings, I have been ignoring them > for now. However, I started wondering if "INFO" message is a red-herring > and thinking there might be an actual problem somewhere.