Could it be for 1040 line 38 estimated tax penalty? Did you have an amount on line 38? The underpayment penalty amount Turbo Tax calculates on your 1040 or state is only an estimate. Turbo Tax can not figure it accurately because they don't know exactly when the IRS or state will get your return and tax due payment. It's very common and normal and expected for the IRS or state to bill you for more or send you a refund. Or you elected to have the IRS figure the penalty for you.
