awkward

I have a friend. A male. A coworker. I have respect for him because: 1. he's smart 2. he's funny 3. he's a good dad and seemingly a good husband. However, I'm starting to feel weird around him. He seems to be going out of his way to have lunches together, to find common interests, stuff to talk about, to get into my beeswax, to flirt? I can't tell exactly, because he's rather introverted. At first I didn't think anything of it, but now it's getting awkward.