Were the markers made of spiral wrapped paper? They could be china markers or wax pencils.
Besides, how is he to know that you aren't interested in taking his course? By the sound of your question, it seems that you have some interest. This could be a good opportunity to introduce yourself, find out about the courses offered by the college and decide which ones to take.
Even if you are not an art student, there are bound to be open elective courses for students in other majors. If you are not enrolled at the college, this would be an opportunity for you to find out whether you do want to enroll. You probably don't even have to enroll full-time. There might be part-time or evening courses for you to take.
Even though I only work part-time at my local college, I have a key to the darkroom there because I occasionally volunteer to be the darkroom monitor when the prof. doesn't have time to be there himself. I clean and straighten equipment and supplies. I replace chemistry when it gets used up and I take out the trash. When the students have trouble, I offer them advice or go with them to the teacher's office to help them solve the problem. In return, I get free roam of the darkroom in the evenings or during mid-term vacations. One hand washes the other, doncha know!
Bottom line: Ask!