Just $37? That seems like a small amount. Did you have a tax due on your return? When did you pay it? Maybe it's interest on it or a penalty for owing too much on your return. The letter should say what it's for.
Turbotax calculates an ESTIMATED underpayment penalty based off the info you entered and the filing deadline but the IRS/State reserve the right to bill you for more penalties and/or interest based on the payment info they have on file and when the balance due was actually paid.
If you are not contesting the IRS finding but you believe TurboTax made an error you must contact TurboTax to file a claim for refund of penalties.
TurboTax hopes you won't read the fine print because you can easily invalidate your claim and end up with nothing from TurboTax.
Also , you must show it was a TurboTax error, not your error.