MobileMe Push Calendar to iPhone

I have an iPhone 3G and am also a MobileMe subscriber. I have been updating my calendar at via a web browser in Mobile Me, and the iPhone does not get the push update. I have to disconnect "push" sync, get out of the settings, launch the calendar, and then go back and turn it back on again to get the update. Is this phone side or server side? And what can I do to fix it if it's on the phone side.

Thanks!