In the 1940's, some gnostic scrolls were found in Egypt. They are dated from around A.D. 350-400. Irenaeus, the orthodox Bishop of Lyons, refers to other gospels written by heretics. Irenaeus wrote his work around A.D. 180. He could not have refered to 'other' gospels if there were no original gospels existing at that time.
Check out: gnosis.org for more info. It is very interesting.