Can Someone Be Born Again For Years and Not Know It?

Cases of Conscience - Book 1 - Case 10 "Is it possible for a person to be regenerated, or born again, and yet for many years after, fear he is not? And may a person no way doubt of his regeneration, and, at the same time, be an unconverted person? If we consider the mental circumstances of the personregenerated, that there are yet the remains of sin and unbelief abiding with him, and that the best are much clouded with ignorance, as well as liable to the bewildering temptations of deceitful friends; we need not think it impossible for
a regenerate person to be afraid that he never experienced that gracious work upon his mind.