EDIT: Next time let people know whats on your account, the fact you played 90 minutes made me think you already had it since asking.
Your own fault for not giving more information about why it was on your account.
EDIT2: Also this Link
So many ways to get a beta invite.
[Edited by DABhand, 11/9/2012 11:25:26 AM]
It's widely known that you can have DotA 2 in your inventory without having an invite...