Does Google perform automatic updates of IE toolbar?

Last week I installed the Google toolbar to IE 6 and it's been working
fine. Just now, out of nowhere, my Webroot Spysweeper interrupted my
work to tell me "A BHO (Browser Helper Object) is being installed in
Internet Explorer" as an add-on. Does Google do automatic updates of
its installed base of toolbars without informing users? Otherwise, I'm
not sure why this would happen without my requesting it. Thanks.