During this one episode we have at least five iterations of our understanding of Mycroft's character:

Ha!  Thanks for the explanation.  What does white mean?  Tracking?  One note, though — about 6.5 minutes from the end of the episode the white haired Decima guy is driven to the New York Public Library and the phone booth. The tracking box over the car he's in is white, from two different cameras, but he obviously…

I haven't seen a discussion of this yet, but in the camera views from the Machine's point of view in this episode, root is given the same "box" status as Finch and Reese.  Doesn't this imply that she has the same trust level they do?