Check you mail at the tower. Get past the introductory mission. Once you have it, you can get as many as you like from the special order vendor... in case you delete it by mistake.

Having the same issue. Redownloaded the DLC several times and installed it, but it still hasn't shown up in post master yet. I simply bought a Sparrow in the meantime, until the DLC pops up.

I'm having the same issue on 360. I have checked the postmaster and attempted to redownload. I still can't get it