XenForo_Phrase::__toString() error


Well-known member
Had a look at the error file in my root directory of my site and found this error:
[18-Sep-2012 01:58:53 UTC] PHP Fatal error: Method XenForo_Phrase::__toString() must not throw an exception in /home/xxxx/public_html/library/XenForo/ViewRenderer/Xml.php on line 70

Any idea what this means and if I should be concerned?