I kinda had a similar experience to you last year at AS.
I'm a male and it was in chemistry.
Female teacher was clearly expressing more interest in me than the rest...people took the piss blah blah but it stopped luckily!
Just be careful OP, not much to say I guess
Have you given him any reason, the slightest reason to make him feel more "interested" in you.
I'm currently training to be a teacher and I do a teaching assistant role in a secondary school which is teaching students mainly aged around 12-16 (but I do help out the 6th formers from time to time)...
Teachers are just humans like you. Some teachers are attracted to their students. It is a sad, but true, fact. I can assure you also that MOST teachers will be much much more experienced than you with the opposite sex and will very easily be able to play you. The actual training involved in becoming a teacher considers the sort of relationships you have with the students and quite frankly it doesn't matter what age you teach (be it primary, secondary or higher) it is unprofessional (to say the least) to get involved with a student.
You should bear the above in mind should this turn out to be a case of the teacher having feelings for you. If he has feelings then i'd strongly advise you to just ignore it politely. It is unprofessional for him, and it is unprofessional for you too.