Mine hasn't arrived yet either. I contacted Delta through contact us and got an almost immediate response telling me that since I requalified in the in last half of December that mine would be among the last sent out. And that I shouldn't be concerned.

Dear Mr. mot29,

Thank you for contacting us.

Customers who qualify for a new Medallion tier in the last half of
December or who requalify for their same Medallion status will usually
receive their Medallion credentials around the end of February. We show
that your credentials are currently pending and should be sent out
shortly. We apologize for any inconvenience and thank you for your
patience.

Thank you for your support as a Diamond Medallion and Million Miler
member and for trusting your business to us. Be assured, we will make
every attempt to serve you well; we are focused on the future and look
forward to our continued business relationship.

Sincerely,

fake name deleted
Diamond Desk