Does this sound a little crazy?

I was talking to my boyfriend yesterday and he always says that he doesn't mind me having sex with other guys. And before he would ask me all the time. Most of the time if I had been with someone else most of the time the answer was no but anytime I did say yes he seemed upset. He's really easy to read btw. Anyways he actually told me that he didn't mind if I slept with someone else but that he wanted to to tell him if I did. He said it would hurt his feelings if I didn't. We are pretty open and honest about stuff with each other but I don't know I just thought this was a little weird. Any thoughts?