There have been alot of reports about 3G data dropping on some devices. I also had this problem and the fix is to deactivate your device for a few minutes. This is done by activating another Verizon device such as an older non used phone for a few minutes and then reactivating your current device.
The easiest way to do this is to go to the activate new device tab on the My Verizon website. It can also be done by taking your device to a store or a call to customer support. If you do it yourself only takes a few minutes and is very easy and works. Remember, a weak or dropping signal will decrease your battery life as well.
Just a little FYI.