Form 1099-B generally isn't issued for sales activity within an IRA or other tax-free account. If you received a Form 1099-B, and the taxpayer ID it was issued to matches your SSN, then it sounds like there are some securities held in non-IRA accounts.
If that doesn't match your understanding, you'll need to discuss this with the financial institution that manages the accounts. If a 1099-B was issued to you, then the IRS is certainly going to be looking for this information to be reported on your return. You will need to amend it.
Are you sure it wasn't a 1099R ?