Maine and Nebraska allocate their electoral votes differently from the other states. Instead of winner-takes all, they elect one elector based on the vote each individual congressional district and the last two electors based on the total state-wide vote.

Normally Maine is uniformly enough (D) and Nebraska uniformly enough (R) that this makes no difference in practice. But this time Obama has a realistic chance of winning an elector in Nebraska. However, your graph doesn’t seem to allow for this situation.