My Halo Wars flame decaled warthog is not there?

[crookdabnoutlaw]

I just picked up my copy of halo wars and used the code to get the flame warthog. now when i am playing the game i notice i cannot make a flame decaled warthog. ive only played the first two levels and a skirmish against the computer and cannot make the flame warthog. anyone know if there is something im not doin?? any help would be appreciated..