I have to say I have had far scarier situations during lessons than this, so I am laughing quite a bit. I am having a hard time taking you seriously.
First of all, why are you looking so much? I know that sounds silly, but it is a serious question. "Out of sight, out of mind" as they say. Unless you think he is going to try to pull something on you, I would just not look and forget about it. It's no big deal.
Let me put your situation into perspective a bit:
I do understand that there may be reason for concern, generally speaking. I teach mainly girls ages 8-17 and I am a 27 year old male. I was completely freaked out one summer--a student, I think she was 14 at the time, came in for her lesson. She was warm so she started to take a heavy shirt off since she had a tank top underneath-- generally this would be no big deal. Well, her tank top came up too, she had no bra on, and she accidentally flashed me everything she had. She apologized and said it was no big deal. I, on the other hand, thought I was going to die and go to jail for the rest of my life. It took me two months to get over that 4 second event. I was talking to her at the time, so I was looking in her general direction before turning around so fast that my neck cracked, but I felt so horrible about it anyway. She just laughed at my reaction.
I felt better after talking to some guitar teachers who mainly have high school age boys and girls who want to be "rockers." These teachers have students actually ask them out on dates a few times a year. I had a 17 year old ask me out for coffee last week as a matter of fact. I would talk to her parents about her behavior, but they are freakier than she is, so I just left it alone.
So, anyway, I am just trying to put things into perspective for you. Maybe this helps, or maybe it doesn't. I simply wouldn't worry about it. I mean, what are you going to accomplish?