It's extremely normal to discuss your dating past, but it's in conversation, over weeks, months or years. It just comes up. It's not normal to be grilled on it, no.
I'd actually be hard put to remember a lot about sex I had 27 years ago. I've just had a think and my body count wasn't even in double digits and yet I still don't remember the surname of two of them anymore 😅 Clearly, they made an impact.
I was married a long time after that and then single and had no interest in dating for a couple of years. When I met my second husband we chatted, over weeks, months, whatever and got an idea of one another's sexual past. It was out of interest more than anything else, just conversations like everything else about us.
I wouldn't be happy to have a spotlight turned on me and it's weird he was fixated on it, yes.
He's not going to mature out of it, so it's fair if you throw this one back.