Xamarin.Forms 1.2.2 pre 3 - PushAsync after WebService Async call problem only on Android

Hi,
I try to change page after an Async call to a web service (on the webservice_Completed event) i got this exception (Only on Android):

Android.Util.AndroidRuntimeException: Only the original thread that created a view hierarchy can touch its views.

Here's the code:

myWS.myWSClient svc = new myWS.myWSClient();
svc.GetDataCompleted += svc_GetDataCompleted ;
svcGetDataAsync();

 void svc_GetDataCompleted (object sender, myWS.svc_GetDataCompletedEventArgs e)
        {

             AppBase.AppNavigator.PushAsync(new myNewPage());

        }

How can I do?