Google calendars not updating to iphone 4

When I update my Google calendars on the google calendar website the updates do not appear on my iphone4. If I update the calendar on the iphone they immediately appear on the google calendar website.

XX--If I go to settings/calendars/Gmail on the iphone and turn calendars off, then back on the sync happens and the calendar on the iphone updates properly within a few seconds.

On my previous iphone 3G I did not have to do the step described above marked by the XX

Any ideas whats going on here?