Soo it looks like I will be receiving my credit after all, I have been exchanging emails with the google support. Initially they gave me the noob email asking if I did this and this.
I responded and said I thought that I didn't receive the credit because I activated after october 1st (even though I bought my tablet at the end of august)
I guess the problem was because I have more than one payment method on my google wallet account (my japanese mobile phone) and because my billing address was set to Japan when my tablet was activated I failed to receive the credit because of that!
But support said if I create a new wallet account and have only a US billing address and payment, that they will give me credit there.
So it sounds like they will give me credit, just not on the account I want to receive it on. I'm happy that I'm getting it, but would be happier if they could just add it to my main gmail account.
Oh well, I guess I'll wait and see if it happens, but it sounds like I will receive the credit!!