You know, motorheadprime -- I am not sure what gives; but FWIW I wish I had your username.
Did the data alert come from your device itself, or from T-Mobile? I know that you can set a data alert on a device using the phone's operating system, but if the "month" for that alert isn't timed with the start and close of your T-Mobile bill cycle, it will give you a false warning. Let's say the phone's data cycle starts on the first and ends on the thirtieth; but your T-Mobile bill cycle starts on the 11th and ends on the 10th of the following month -- the phone is going to alert you that you've used your data more quickly, because it's counting all of the data from the first through the ninth. Does that make sense? Could this be an explanation for what you're seeing?
Just checking in here to see if you still had questions on this.