Is my teacher interested in me?

Yesterday I (F18) told my teacher (M30s) I had something to ask him, in regard to the lesson, and he told me to wait there after class. After all my classmates went away I asked him my question, which was very quick to answer.
After answering, he randomly started talking about a sport we are both passionate about and after also this topic came to an end, he introduced another random one, and then another. In the end, we spent about 20 minutes talking, and I even arrived late at my next class lol.

Furthermore, he had asked me multiple times to go play tennis with him once the school year end and he is always very cute and nice to me (and to all students, male and female, to be honest).

Is he just being friendly or do you think he likes me? I mean, it's not a very common behavior (spending time 1:1 randomly talking after class, inviting me to do something together outside school in the future etc), is it?

PS. I think he has a girlfriend, even though I'm not 100% sure.
Is my teacher interested in me?
Post Opinion