Wow, no 638...who does that! Any and all awards should be presented in Green casing with the 638 on left and cert on the right as you open it. I can only sense that being in deployed environment might have something to do with it. This is not the normal practice at all!
Anyway, the cert only gets iPERMED and as long as the PO number is on it your good. Keep comms with that unit is your only hope.