I'm with Tanza. It's normal for many Basenjis. Just let it go.
You also need to understand that a Basenji isn't going to be as easy to train as most (all?) other dogs. LOL I'm actually quite impressed you have him walking as well on the lead as you do. This is not so much of a "wasn't done right when he was a puppy" as it is "that's how they roll".
The good thing is that if you're in Africa your little guy will understand* how to sneak attack and attack the lion from the rear so as to distract him from his task of eating you!
[edited: substituted understand for undertones]