It did seem high when I wrote it (which is why I added "if I remember") and I even looked back at that salary index table I referred to in Paul's thread. If the rate was 15 an hour in 1978 then it would around 45 an hour today based on "average" salaries today being 3x what they were in 1978.
At the time, the GI bill provided x number of hours of tutoring, and my tutorees, all 2 of them, were referred to me by the instructor (who knew me because I hung out a lot in the astronomy section). I could be wrong on that figure (of 15) but 45 an hour today does not seem astronomical for tutoring, although that would be high if you had a full schedule and managed to charge 2000 hours a year.
Looking at the rate range of (individual) tutors today (30 - 50), I would say that it is possible I was making 10 an hour (but no less). For some reason 15 sticks in my head.