Doesn't matter. It is never too late to explain. Just tell him, "Hey, remember when you said that? It was so unexpected I choked but I want you to know I feel the same way" or w/e you would have said. That's that. Easy as 1-2-3.
Call him up and say you want to go and do something fun together.
Tell him now! If you have a cell phone call or even text him something cute, trust me it is better to tell him a little later than expected then never at all, never live your life with this what if question
he'd probably be wishing he kept his mouth shut...i would be. If you feel the same way he does..just tell him.
I contend he will feel she does not feel the same way, or he has moved to fast and blowned the relationship.
Likely he would have felt a little confused. Maybe wondered if you really do enjoy spending time with him or are just doing it because. Sounds like you really do enjoy spending time with him. Easily corrected if you want. Just hang out with him and in a moment say, "You know, I really do enjoy spending time with you, its easy, fun, relaxed, and around you I can be myself." Problem solved, he forgets any doubts and he didn't initiate so there was no pressure for you to agree. :) Hope this helps.