When I was going through boxes of old stuff over the weekend I found some old medical records.
1995-1997 when I was stressed, sedentary, and gaining weight:
Total Cholesterol 197-230 (less than 200 "desirable")
HDL 44-52 (above 60 "some protection against heart disease")
TC/HDL ratio: 4.42-4.48 (ideal below 3.5)
Total Cholesterol 179 (less than 200 "desirable")
HDL 68 (above 60 "some protection against heart disease")
TC/HDL ratio: 2.63 (ideal below 3.5)
So I think that positive difference in ~11-13 years is probably completely due to lifestyle, exercise level, and stress reduction. It's not age or body fat, since I'm over a decade older and still fatter now! Of course, it's possible it could have just been a random incorrect test in June too.
The lowest body weight that I could find was about 20-22 pounds lighter than I weigh today, in 1991 when I was 34 and getting a lot of exercise. That's not a bad goal for the next year.
Getting healthier, not older!