Well my take on the situation is that if you keep asking him if there is a problem.. there will be... If he says everything is fine then everything is fine....at least give him the benefit of the doubt that he is telling you the truth....

He may have something else going on in his life that is distracting him....

Give him a week or so...if you don't see a change ...then start doing other things to take up your time...Also I would tell him that if he needs some time then to call you when he is ready to tell you what is going on.....this will give him some space to think...and then maybe you will get an answer....