the info you provided indicates it was not the preparer's mistake so you might get charged.
It is also likely, that the IRS will eventually catch the omission even if you don't amend. In this case they will bill you for the taxes, interest and late payment penalties. Amending now, will save some penalties and interest because it could many more months before the IRS issues the bill. interest increases daily and penalties increase monthly.
my recommendation would be to go back to the preparer and find out what the charges would be before you decide to either wait for the bill or redo your return using TT.
