Why did he got worried for so little?

So, I have this crush on a guy, and sometimes I think that he has for me too. A few days ago, I saw him on the store, and he was with some girl I didn't know. My only reaction was to say something like "hi! how are you?". A few days later, he asked to me why I spoke with him so fast. Obviously, I was embarassed because he entered there with some girl (she was only with him, not holding hands or anything), so I invented some lame excuse lol
Anyways, my question is: why he asked me that? It is possible that he might like me?
Thanks

From my observation, this is what i would read about that.

You were either nervous, didn't know what to say,
or were put on the spot and that's all that came out.

Maybe he knows you, but why would you think that he would like you ?
Your the one that has a crush on him.

If you really do like this guy, ask him out and see his response, if he gives you some
lame excuses, you'll know he's hiding something by the why he says it.

She could be his gf. Is there any way you can find out if hes single

What kills me is that he has someone already. This is why i reacted in such way... So the only thing i can do is forget about him....

She might be. He said to me that he has a gf. This is why i reacted so bad when i saw him. Just hope that he didnt noticed that... He might not like me, at all.

He was probably just curious. My mother does the same to me if I sound different.

he told you he has a gf so let it be