When I started training in the early 90s in Australia, we only had Dan certificates issued by Saito. I distinctly remember that after returning from a trip to Iwama my sensei at the time (maybe '93) announced that Saito would now be awarding Dan certificates from Aikikai (at 4 times the cost, which is why I remember, think I was a broke 3rd-2nd kyu at the time
). I had no ideas of the intricate nature of Aikido politics at the time, I just trained, but I assumed that this meant the Saito was not giving Aikikai ranks before this.
Aikikai Dan grade certificates were certainly issued via Saito Sensei well before the early 90s. I just checked my Yudansha card and my aikikai shodan was issued in 1987. All my Aikikai Dan grades, up until my godan in 2005, were via Sensei so I guess it depends on which group you were affiliated with. As you say- politics!