Hi Sean Overman,
I successfully reproduced the described behavior. Indeed, this is unexpected and will be fixed for our next release. You can also download and use one of our next internal builds, which will also have this bug resolved.
If you download the latest official version of RadControls (Q2 2009 SP1, released yesterday), you can workaround the problem by setting the new property AllowOutOfRangeAutoCorrect to "false". In next version this workaround will not be necessary.
Sorry for the inconvenience. I have updated your Telerik points for bringing the issue to our attention.
the Telerik team