It was only for a certain amount of time that you would get it. If you bought the dark below past jan 15 (iirc) then you didn't get the tumbler. Try going to the special orders lady. You can buy a new one from her.

You are right, I have looked on here it says if you have either the season pass or the expansion I : Dark Below, you should receive it as soon as you purchase it. I have yet to receive it even though I bought it three days ago.