Is he just being nice or flirting?

Hi! So I have this new coworker who started a few months ago and I can't tell if he's flirting with me or just having banter. He's often very jokey with me and even messages me on teams funny comments. When he first started he stopped me in the hallway to get my instagram, and then messaged me at midnight saying "where's my cupcake" as I had brought in cupcakes to the office that day. He's also very complimentary towards me, saying he likes my hair, or if I wear a certain colour that it suits me.

I kind of think it's all in my head, especially as he is wayyyy out of my league, but a small part of me hopes he is flirting.

What do you guys think?