What does it mean if a guy is "heteroflexible"?

I've been talking to this guy and we spoke about our college years. I mentioned the first time kissed a girl. I'm bisexual. He said he's only ever been with one male every and it was his best friend. Besides that he likes women. I asked was he also bi and he said "I think I'm more heteroflexible." I just said ok because I didn't want to seem stupid. Was curious if anyone knew what that meant.