What does it mean when your guy friend asks you if you're a virgin?

Okay so I have this guy friend and we're only friends. I've known him since junior year in high school but we started talking recently like everyday. He's a cool person to talk to but I have no feelings for him whatsoever. We talk about a lot of different things and our conversations are always chill and interesting I guess. But he asked me if I was a virgin and I got completely weirded out and offended. I hate when people ask me this question because it's not their business. Then he goes "we talk about a lot of things I thought we could talk about sex guess not" and we had a small argument and I kinda went off on him. So I'm thinking now that his intentions are not good even though we've talked about things like this before and he's always complaining about how society thinks all men are corrupt and he's not. What does he mean? Did I have a right to get offended by his question? He later apologized and said it was rude of him to answer and respected the fact I didn't answer.