Generally, you don't owe a penalty as long as at least one of these statements is true.
1. You owe less than $1000 with your tax return.
2. Your payments into the system (estimated payments or withholding) is at least 90% of your tax liability this year.
3. Your payments into the system are at least 100% of your tax liability for last year.
If Turbotax thinks you owe a penalty, then you probably didn't have enough withheld at your job (too many allowances on your W-4). The amount of extra tax due on a $1000 prize and one savings bond should not, by itself, push you into penalty territory. Turbotax may also be incorrect.
You can decline Turbotax's recommendation to add a penalty, and let the IRS bill you if you really owe a penalty. When you get the bill, you can request an abatement of the penalty if this is your first time owing a penalty.
Abatement https://www.irs.gov/businesses/small-businesses-self-employed/penalty-relief-due-to-first-time-penal...
