Indeed I was able to observed the described behavior. However I'm happy to inform you that our developers has managed to address the issue in question. Thus the fix will be included with SP1 of Q3 2009 RadControls for ASP.NET AJAX, scheduled for the mid December. Meanwhile you may check the next internal build, which should contains the fix too. I have also updated your telerik point as a token of gratitude for bringing this to our attention.
the Telerik team