I think he’s just dipping his feet in the water to see if it’s hot or not.
I do think he should have just asked you directly to go on a date..
He’s assuming that because you haven’t talked about it for 3 weeks, he probably thinks you have many other options (which is completely fine). Doesn’t matter if you’re not exclusive or not, if you did have/went on another date with someone, you have to be honest and admit that to him so he knows where you’re at in terms of time.