If you haven't talked too much about limits beforehand he could be just starting slowly. Communication is the key. I started with my sub by instantly filling a rather long modified bdsm checklist, because without clear understanding of hard limits/likes i get too careful as i might actually break her. And if i am careful, only way i am able to enjoy the sex is imagining what it should be like.
When i know ALL the hard limits i can work with, it gives me freedom to be myself and in get instantly super confident and the feeling of freedom to be myself is intoxicating.
Then again, not everyone is a sadist or dominant by nature even if they enjoy bdsm. But you can test it to be sure.