I've noticed the same thing on my new Tilt 2.  I check the connections from time to time and see MEdia Net is connected.  I go into the Connections settings and see Data Connection has turned itself on.

My concern is that I'm burning up plan data minutes while this connection is happening.  I've caught it once where it had been connected for a couple of hours, and I have not idea what might have been downloading.

It seems this is normal, as the first responder indicated.  However, does this add significantly to the data usage?

Thanks