If a higher premium has been agreed on account of certain risk-aggravating circumstances, and these circumstances have ceased to exist or become immaterial after the policyholder has submitted an application, or after the contract has been made, the policyholder may demand that the premium be reduced commensurately from such time as the insurer is in receipt of the demand. This also applies if the assessment of the higher insurance premium was occasioned by incorrect statements made on the basis of a mistake on the part of the policyholder concerning such a circumstance.