Republican districts moved right in 2012 and Democratic districts moved left.
For the most part the movement left in Democratic leaning districts and right in Republican leaning districts lessened as the districts moved closer to the middle. This is the exact opposite of what the legislatures would want. If you're Democrats you want D+2 districts moving 3 points left and don't care what happens in D+20 districts.
The popular meme is that the country is becoming more polarized and this seems to confirm that. Either voters are conforming more to their neighbors or Republicans are moving to Republican areas and vice-versa.