How?

So there's this guy at my work. Every time I see him, he always asks me the same thing. He always asks me how I am, I will say good, but then he will always ask me if something at home is wrong. And I always think to myself when he asks that why would he ask that. It's odd. I told this to my best friend that I think its odd, cause its like he knows that something is up, and that he can see me hiding it. He can see through me? But I don't get how? I am usually always happy, but yet he still sees through it. It scares me a little I admit that. I don't really even know him, or say much to him at all, just whenever he says "hi" and say it back. I don't get it. I have been stressed a lot lately, but I don't see how he could even see that, or even know that without knowing me.

Does this not sound extremely odd to anyone else?