Unexplained constant data usage on iPhone 5

My wife and I just received iPhone 5's yesterday, our first smartphones. We're enjoying them but then last night I noticed something strange. Whenever the phone is on cellular data there is a constant data usage taking place. When I go into settings and look at usage of cellular data I can see it increase by a couple of KB each time I recheck it. Going back and then back in takes only about a second. So very rough calculations indicates that this adds up to about 170 MB per day when on cellular! I've even turned off everything I can think of to try and address background data usage: push notifications, location services, all iCloud services, etc. it still uses it.

Is this normal? I did some searching here and saw posts on folks having mysterious data transfers post midnight. But this is something that's happening constantly. ANy ideas?