I'm a Viet Nam Vet and received my honorable in mid '73 after 5+ years active duty (Capt, USAR). I do recall receiving a letter from DOD (not sure exactly when, but I don't believe it was all that long after separation) asking me whether or not I wished to retain my USAR commission, which I declined. Do you recall if you also received such an inquiry and if you might have elected to retain your commission?
I am a Vietnam vet as well, and unlike Kerry, served my year there. I did receive such a letter and if I recall correctly, I had to let them know if I wanted to retain my commission and remain in the reserves. Otherwise I would be separated. I took no action and received my honorable discharge as a LCDR, USNR.