He may be wanting to hang out for a little bit and talk or watch a movie because he may be flirting with the idea of what it would be like to be more than a FWB.
Now that some time has elapsed since the both of you became friends with benefits and started hooking up, he may have reached the point where he wants to spend more time with you.
He may actually be just as confused as you are in terms of what he wants.
Initially, he may have thought that he just wanted to be a FWB.
However, his desires may be changing.
At this time, he may be trying to see whether there is more to your relationship with him than merely physical chemistry.
If he discovers that he doesn’t really feel that much chemistry with you when he hangs out with you, he may stop trying to hang out with you and revert back to only being a FWB.
However, until he finds that out, he may continue trying to hang out with you.