MightyBoard Rev G. grounding?

[justbuchanan]

I'm in the process of replacing my Makerbot Replicator 2's control board with the Geeetech MightyBoard Rev. G. I noticed that the sd card slot's metal casing seems to be connected to the negative power terminal. I discovered this by connecting a multimeter/voltmeter between the positive terminal of the input power adapter and the sd card casing. Is this intentional or is it a problem with my board?