Payment due after filing adjustment but IRS says you don't have anything due

I have unique situation. I made a mistake in 2019 taxes due to which I got some extra refund about $500, I filed adjustment of 1040 when I realized my mistake and paid back the due amount whatever was calculated by Turbo tax. Few months later I got a letter from IRS saying I owe $9.41 due to change in increase/decrease of interest (or whatever) and due date is Jan 2020. I didn't see the letter until I started filing in March and then after realizing I already missed the due date, I called IRS office to find the new amount  and if there are any penalties. They looked up my record and said your account is not showing any due amount. I told them the letter say $9.41 is due, and the guy said something like 'if its under a certain amount we don't chase it'  (don't recall exactly what reason he provided, vaguely recall he said under $25). I was not able to complete the tax in time and filing it now at the eleventh hour 🙂 

 

What's the recommended option to handle this case:

 

a) ignore, since IRS says my account does not show any pending balance

b) contact IRS again 

c) pay like $15 to be on the safe side when filing tax by Friday. If so, where do I enter that amount in Turbo Tax?