Note that the mentioned version of RadControls has been released before the latest IPad browser version you are facing problems is. Therefore we hadn't tested the previous version of our controls into this browser and some issues are not excluded.
Could you please update your application to the latest official release of RadControls and verify if the problem still persists.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed