gedit produces unexpected error messages

After <Ctrl-Shft-k> to turn off the highlighting, I saw these error messages in the terminal:

(gedit:5413): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(gedit:5413): GLib-GObject-CRITICAL **: g_signal_handler_block: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(gedit:5413): Gtk-CRITICAL **: gtk_entry_set_text: assertion `GTK_IS_ENTRY (entry)' failed

(gedit:5413): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(gedit:5413): GLib-GObject-CRITICAL **: g_signal_handler_unblock: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: gedit 3.4.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-24.37-generic 3.2.14
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
Date: Wed May 9 15:27:12 2012
ExecutablePath: /usr/bin/gedit
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
ProcEnviron:
 TERM=xterm
 SHELL=/bin/bash
 PATH=(custom, no user)
 LANG=en_AU.UTF-8
 LANGUAGE=en_AU:en
SourcePackage: gedit
UpgradeStatus: Upgraded to precise on 2012-05-01 (8 days ago)