I remember mine being in a ziploc bag just laying on top of my games. At least I think it was... it's not like am a KS junkie and have received tons of games recently. Hmmm, I hope the wife does read this thread.
When my box came, it included different components. One of these was the promo cards (including Theseus), in a separate, small ziplock bag, inside the large mailed package. The ziplock bag was outside the base game and Atlas expansion; had I not noticed it, it would have been easy to throw it away with the package.
I echo the earlier reply: try looking through your packaging materials -- you'll probably find it.