Hi James,
This is a known issue in the current release I'm afraid, the labelling of the classes is misleading - the maximum value in a given class is below that labelled. So in your example, the value of $35,443 is in class 2 - you should see if you find a feature that has the boundary value, it is symbolized correctly in the map with the higher group's symbol. This is on the list of things we'd like to address for the next release; however as it's not currently fixed in our working builds so I cant promise it will get fixed for the next release.