My husband won't tell me what's bothering him....?

Everything has been good lately, no problems. Went to a bbq yesterday and had a blast. Everything seemed fine this morning. Then later I could tell something was on his mind. Asked him what was wrong..he said nothing. I knew he was fibbing, kept asking..then he said he didnt want to talk about it..ok...i asked if it had to do with me, he said .."a little" so i kept asking..he wouldnt tell me. Then later on i asked again, he said that it didnt have to do with me now, ok then he said he didnt feel like talking about work...so then i asked him again later and he said it was embarrassing but it was nothing. I have been with him 6 years almost 7...if it is really nothing then why wont he just tell me so i'll shut up and stop worrying about it! What on earth could possibly be bothering him? Men in particular please tell me what would be bothering you to the point where you would not tell your wife about it??????????