I thought this was a paint error at first, but all of the sith training mauls I have seen look like this.
I just checked my carded TSC Mauls, and all three of them have the appropriate red painted chins, so the all-black chin variant/error is definitely not across the board...
Also, since I haven't scrolled back through this whole thread, I assume someone's pointed out the many incorrect stands included with some of the figures, and the fact that some/all of them have been subsequently corrected by Hasbro, or changed to something more appropriate. RS has had several articles up on the topic. Considering you can barely even see the stand if the figure is still carded, I'm not sweating those variations, but I'd at least like to have the corrected stands for my openers.