--- image.module	2008-08-17 01:44:24.000000000 -0700
+++ image_derivative_msg.module	2008-10-15 13:15:58.000000000 -0700
@@ -660,7 +660,7 @@ function image_load(&$node) {
     // If the file is missing or created after the last change to the sizes,
     // rebuild the derivatives.
     if (empty($node->images[$key]) || !file_exists($node->images[$key])) {
-      drupal_set_message(t("%title's %key derivative image %filepath was missing. The derivatives will be rebuilt to regenerate it.", array('%title' => $node->title, '%key' => $key, '%filepath' => $node->images[$key])));
+      watchdog('image', t("%title's %key derivative image %filepath was missing. The derivatives will be rebuilt to regenerate it.", array('%title' => $node->title, '%key' => $key, '%filepath' => $node->images[$key])), WATCHDOG_NOTICE);
       $node->rebuild_images = TRUE; 
     }
     else if (filemtime($node->images[$key]) < variable_get('image_updated', 0)) {