Index: docs/ref/contrib/messages.txt
===================================================================
--- docs/ref/contrib/messages.txt	(revision 16861)
+++ docs/ref/contrib/messages.txt	(working copy)
@@ -183,6 +183,10 @@
 ``RequestContext``. Otherwise, ensure ``messages`` is available to
 the template context.
 
+Even if you know there is only just one message, you should still iterate over
+the ``messages`` sequence, because otherwise the message storage will not be cleared
+for the next request.
+
 Creating custom message levels
 ------------------------------