I went to a concert with my guy friend, who I like, and I was flirting with him by touching him, gazing at him, and whatnot. He also would look at me for a long time, and then he would place his hand on my back, guiding me as we walked a few times. He's never done this before. What could it mean?

There was a large crowd and he did not want to lose you??

How old are you

Have the two of you ever went to a concert together?

Don't read too much into that until he gives you more of an idea that he likes you.

That you were walking too slow and he was politely telling you to hurry.

Ask him, we aren't mind readers

It means he likes you just like you like him.