I got my new iPhone 5 on AT&T on Thursday. When I did, AT&T reset the monthly data usage to 0.0 MB. It's now Sunday, and it's saying that I've used almost 5 GB of data since Thursday. What could be the cause of this? All I did was do some light web browsing, email, Twitter, Facebook, and watch a few YouTube videos. I find it highly unlikely that I've used 5 GB of data in 4 days, as I've never gone over 2 before in a month.