You're not crazy (or maybe I'm crazy too!).
I just re-read the e-mail and re-checked their Kickstarter page and there's no mention of a T-shirt in any of the tiers (at this time).
I am a community moderator, here to assist, keep the peace, and keep these boards clean and friendly for all. I am a volunteer, and not a Telltale employee, and my opinions are my own.