Why does my cat act like this..?

My cat, Deckster was found about 2 years ago. We found him underneath my deck. And after that he has been scared of the outdoors, which I didnt mind at all. But now he goes out everyday, and im ok with it. Just scared I might lose him? When I call his name or Whistle he usually comes to me. But tonight he didnt...guess where he was? Underneath our deck. Just laying there for almost 4 hours. I love seeing him explore the outdoors, but will this continue?