I have. I can't find a single document from the Tribe itself even discussing MazaCoin, let alone adopting it as their currency.
You will find announcements here:
http://cryptominers.freeforums.org/official-announcements-f4.htmlYou will find the Memorandum of Agreement.
Here is the info for the director (Office of Economic Development):
David T. Mills, Director
PO Box #669
Pine Ridge, South Dakata 57770
Tel (605) 867-5771
Fax (605) 867-1471
Give the man a call.