What does the fight with his friends have to do with your question?
There's no way for US to tell if he's flirting, since we don't witness it. Just come out and ask him.
I have become friends with a guy over the past few weeks. He got into a fight with his two friends and if we see each other we always talk. He is a nice guy, very polite, but seems to be very friendly & idk if he's flirting or not?