backward-kill-word is not refreshing correctly

[Matt]

Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: i686-pc-linux-gnu-gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib  
-DDEFAULT_PATH_VALUE='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
 -DSTANDARD_UTILS_PATH='/bin:/usr/bin:/sbin:/usr/sbin' 
-DSYS_BASHRC='/etc/bash/bashrc' -DSYS_BASH_LOGOUT='/etc/bash/bash_logout' 
-DNON_INTERACTIVE_LOGIN_SHELLS -DSSH_SOURCE_BASHRC -march=pentium4 -O2 -pipe
uname output: Linux ice.filescope.com 2.6.25.10 #5 PREEMPT Thu Nov 27 16:10:07 
EST 2008 i686 Intel(R) Pentium(R) 4 CPU 1400MHz GenuineIntel GNU/Linux
Machine Type: i686-pc-linux-gnu

Bash Version: 4.0
Patch Level: 10
Release Status: release

Description:
        When I type a long string of text and start pressing ctrl-W to 
backwards-kill words, bash deletes the words but doesn't visually refresh (the 
words still appear on the command line). This was not occurring for me in the 
3.x series of Bash.

Repeat-By:
        Write this text on the command line: "sample text sample text sample 
text sample text sample text". Start pressing ctrl-W and notice it takes a few 
kill-words before the words start disappearing.

--Matt Zyzik