You will never know if someone trusts you. More importantly, you will never be able to trust anyone. It is all too easy to accidentally let someone down, even without realizing. You can befriend people and like them as a person, but don't trust them with anything. Not your money, emotions, or life. The world is in the palm of your hand, and your hands alone. Don't expect him to trust you. Just expect him to like you as a person.
he will probably start to talk to you about more personal things, he might say can i talk to you about something or.. just always want to talk to you, some guys might be more open and tell you they trust you. but others might be a little shy and are kind of embarrassed.