Most Helpful Girl
Sounds to me that this may have been the first time he even considered you. Sounds like he's never dated anyone but white girls and when you asked he had to think about it. It's no sign at all to me. He thought about it but probably hasn't made a decision. Give him time. If it is possible, he may start to show you signs of interest. You can respond but I wouldn't ask him out or initiate anything.
I'm black and I am not offended by what he said. I've almost never dated a guy of another race who has dated a black girl. It can change over time but he has not had the experience to change it yet. He probably needs a lot of time and you have to also consider that if he's thinking that what his family may be about. He may think, I would but my parents would hate it so I won't.