I'm glad you didn't report his behavior. As Janin notes, it could be read as paternal just as easily--perhaps more easily, given the absence of any iteration--as an attempt at romance.

But there is also a kind of pedagogic eroticism that isn't really romantic, either. Plato puts eros at the root of philosophy and learning, and any of us who have been in a vibrant, interactive classroom know that its energy is "erotic" in a broad sense: you are sharing a passionate pursuit of learning something and you are affirming each other in the process. If teaching is truly not "filling a bucket, but lighting a fire," then the teacher also feels affirmed when students "light up." There is no professor in their right mind that would describe their classroom environment as "erotic" at this moment, but it is possible that that is the kind of "love" that your professor was expressing to you.

Lovely piece, and well written.