Who is responsible for painting the ceiling?

Hired a contractor to drywall my ceiling. I said i would paint the ceiling, which i did and completed. Now i am noticing the nail heads protruding from the ceiling. The contractor fixed the protruding nails, but said he was not responsible for painting the ceiling and that i was. I would ume that since it was his construction that lead to the protruding nails, he would be responsible for repairing and re-painting... who is responsible?