If you check your account/weekly summary and go to the week you made your Marriott request, the date should be listed on when they will process. My recent experience in January was that they listed as processed, the customer service people via phone stated they were sent in January, but the postmarks on the envelope when I received them were four weeks later for all three redemptions.
Pure speculation on my part is that the request took place while they were transitioning between a 30 day processing time to the new 60 day processing time.
On a different matter, I made three requests for Marriott certificates in December and have not received them not any return communication to four requests. Seems like these certificates have no control over them and if they don't make it into your mailbox you are SOL.
I've earned almost 140K Marriott points to date...I'm only a few thousand away from a 200K award! It will be my luck that it will probably increase to 250K.