In my view, Obama run the race-oriented message when it benefits him.  During these 4 states that you mention, he didn't bring it up.

But when the race goes to the AA states, he brought up the issue.  And a lot of AA are under peer pressure to vote for Obama.  There is a video in youtube that a young AA made, he was called a 'house #igger' because he voted for Hillary.  This peer pressure resonate with what Obama surrogate pressured AA super delegate to switch to Obama.  The remark such as do you want to be the one that stand in the way of a brother and the presidency.  That is a race-oriented message.

In MS he also tried to gain sympathy from AA voters by saying that Hillary circulated the picture of him in muslim garb.  The incident has already be debunked back in OH, and Obama already accepted that Hillary didn't leak the photo.

This is a kind of race-oriented message that I see and it helps him win the AA vote in the south.  But I am sure that he won't bring that up when we move to the north like in PA.

In Idaho and Maine basically Clinton didn't campaigned as much as Obama, probably because Clinton need to preserve the fund.  There were little ads run in those states.  In Iowa, it was the caucus, and obviously Clinton was not prepared for the environment in caucus system.  Obama was more prepared and he deserved to win there.  In Wyoming, Clinton was better prepared for the caucus.  The score was a respectable 7O/5C.