I am 34 (but due to serious lifelong depression and some health issues I truly feel very old, I envy those of you who are young and healthy and those who at least had a chance to feel what it is like to be young.) I have been involved in the TG community for 15 years, and started at 19.
I noticed the same, and interestingly enough that hasn't seemed to change much in the last 15 years, at least in my experience. There were few TV or TS under 30 15 years ago, but today are plenty of TS in their 20s, but still very few "occasional" CDs. I always felt a bit like the odd man out, 15 years ago it was the age gap which didn't bother me that much per se, but today it is the lack of fellow CDs my age (even in their 30s they are not real easy to find.)