I've observed something since migrating off of my iPhone 3GS with iOS 4 onto my iPhone 4. I'm wondering if anyone else is seeing the same problem. Any custom ringtones I assign to contacts on my iPhone seem to be forgotten upon the next sync of the device with iTunes. The ringtone just switches back to default. Anyone else seeing this? Under the contacts section of my iPhone it says that it's syncing over the air with MS Exchange (which is correct) but it is not syncing locally with my Mac. Is this expected behavior? Any way to workaround or fix it?