Gift tax on down payment

My husband and I are planning on buying our first home, and my parents will be supporting us by depositing the down payment funds (150k) into a joint account that we all have. My question is I understand the annualized tax exemption of 30k for couples for gifts, and that the recipients incur no tax on the gift, but will the down payment be eligible for deduction on the lifetime gift tax exemption for my parents? To the best of my knowledge they have never filed any deductions for the lifetime exemption, so if they were to file the exemption and fill out the appropriate form, would the gift still be tax free?