Hi Marc,
If you are fairly young you have been afforded more training in this skill than us old-timers. When I was young and through the early part of my life, homosexuals* were under deep cover and blending in as best they could. I didn't think that there were any among my class-mates in high-school and was too busy in my college years to pay attention. I later recognized that several people (including some friends and acquaintances) I thought were "straight" during those years (late 60s-early 70s) were homosexuals* by hindsight, but that was because my "gaydar" was improving with age, time and experience. Plus, homosexuals* were not trying as hard to blend in. Over the years I have found it easier and easier, but it is not always an immediate perception with those who are not "open" about it and/or don't project it one way or another. Sometimes, depending on the person and circumstances it can take a while.
Consequently, I don't think that the accuracy of your perceptions or instincts in this area necessarily imply a PL as a homosexual*. You could just be enjoying enhanced sensitivity on this issue due to growing up in a different period of time. And, you may just be a fairly perceptive person. OTOH, I also can't totally disprove your hypothesis either. So, maybe yes and maybe no. However, I tend to favor simple explanations over more complex explanations unless the evidence requires. So, I'd personally stick with the idea that you live in a different era and are a fairly perceptive person.
Cordially,
S&S
PS*--I don't know what the current acceptable terminology is in this area, but I can change what I have used if someone is offended. Just let me know.