Yeah, I know it's just a notice but is unpleasant. So, please make a small update to the plugin.
File flicrrss.php, line 226 you are using user levels which are deprecated since version 2.0. Please change 3-rd parameter from '8' to 'manage_options', which has the same meaning:
add_options_page('flickrRSS Settings', 'flickrRSS', 'manage_options', basename(__FILE__), array(&$this, 'printSettingsPage'));