Under the law, you need to amend your return to include this income, even though it's a small amount.
According to IRS Topic No. 308 Amended Returns:
If you discover an error after filing your return, you may need to amend your return…. file an amended return if there's a change in your filing status, income, deductions, credits or tax liability.
Please see the TurboTax Help article How to amend (change or correct) a return you already filed for instruction on how to amend your previously-filed tax return. Wait until you receive your refund to amend. If you owe, you can amend e-filed returns if they've been accepted and paper-filed returns after they've been mailed.
