Many writers and thinkers have speculated about how the first black family has dealt with the what historian Carol Anderson calls the inevitable "white rage" backlash to Obama's election. Having served her time, Michelle seems more willing to take the criticisms head-on. This is what many of us would call "shade".

This line does some work. On one level, it is red meat for colorblind white (and some non-white) liberals who require all black figures to be hopeful (I've discussed this more here: http://www.theatlantic.com/politics/archive/2015/08/between-the-world-and-me-book-club-not-trying-to-get-into-heaven/400271/).

On another level, it is doing some inter-group communication or what Stuart Hall called encoding/decoding and what Mark Anthony Neal translates into "black code" when he talks about Hall's work through modern media cultures. Obama is signaling here that she has noted those who have directed racist, sexist, classist rhetoric at her family. She has taken note.