Of all things to have Fort Knox security, I wouldn’t normally think that a Subway gift certificate would have it. The top of a certificate that I was given says “Do not redeem certificate unless it has a subway hologram, a global image appears when held up to the light and the special ink causes the dollar sign to fade when rubbed with your finger.”
Do you supposed there has been a black market of forged Subway gift certificates? It seems to me that all this security is more costly than the face value of the certificate.