That's actually a very interesting observation. I've taken herbal supplements that (supposedly) increase testosterone in the past. In particular, Longjack extract led to a marked increase in stubbornness, argumentativeness, and using extreme language in my arguments - e.g., "There's no way this ISN'T true!" or "There's no other reasonable way to see it." I had to stop taking it as this was causing interpersonal problems.

On the other hand, this effect doesn't seem to be limited solely to men, so while I may have mellowed with age, I don't think that's the only thing going on here.