How to not smother him or let him slip away?

I have been seeing a guy for a month now that I knew from high school (casual- not exclusive) and he recently got out of a serious relationship. He assured me that he was over this girl and that he was fine, but due to facebook posts I honestly don't think he is. I think that he feels he can't talk to me about it, even though I told him it was okay to still be upset about the whole break up, but refuses to talk to me about it. I want him to feel that he can talk to me about anything but I don't want to smother him. How can I give him his space without making him think I'm okay with him not telling me how he is really feeling?