Of course - my mistake! The apache log refers to the same line of code, however. This might be moot as I see 2.3.2 RC has a bugfix for this error - will try and install and see if I continue to get the error.
[Mon Sep 02 19:13:00 2013] [error] [client ] PHP Fatal error: Call to a member function isAdminGroup() on a non-object in /public/application/views/account/system_permissions. php on line 55, referer: /index.php?c=access&a=index