1UP contacted Microsoft to see if they knew what was going on and received the following official response:
"We are aware that some consumers who preordered Banjo-Kazooie: Nuts & Bolts have not received their redeem code for Banjo-Kazooie on Xbox Live Arcade. We are currently investigating the scope of this situation, but we believe it represents a small fraction of the total number of preorder customers. We encourage anyone who preordered Banjo-Kazooie: Nuts & Bolts and did not receive a redeem code to follow up directly with your retailer's customer service team for resolution."