If you had an exemption from the requirement for having health care coverage the Form 8965 would have been filed with the 2017 tax return.
If you did not have health care coverage from one of the State Marketplaces or from healthcare.gov then you would not have received a Form 1095-A and a Form 8962 would not be required.
The IRS may well have incorrect information about you concerning health care insurance for 2017. Use the phone number on the IRS notice you received and speak with an IRS agent to get more information.