[Plugin: WP Greet Box] Error when browsing media library

When I am inserting an image into a post and click the “Media Library” tab, I get this message:

Warning: Cannot modify header information – headers already sent by (output started at /wp-includes/script-loader.php:633) in /wp-content/plugins/wp-greet-box/includes/wp-greet-box.class.php on line 492

I’m nonetheless able to insert images without issue, but I thought I should report this incongruous conflict with WP Greet Box.