I have had similar fantasies. Even caught her arreola peeking out of her bikini a couple times and held back saying anything (depending on current company) until after I looked to see if anyone else was noticing.
So my fetish started when I was about 13 or so. This was in the 70’s when girls didn’t shave clean. My mom would take us to the area association swimming pool. I was walking past this mom laying out. I took a glance at her crotch and saw some pubic hair sticking out of her swimsuit. That was all it took. If I saw a friends mom there I would go over to ask about him. But really I was checking for stray pubes. That’s probably why I’ve always been turned on by milfs and older women.