It seems that you did not report this rollover on your tax return. There is no good way to report this by filing an amended tax return because it changes nothing but what should have been on Form 1040 line 5a and there is no equivalent on Form 1040-X. Rather than amend your tax return, it would probably make sense to just retain the documentation necessary to show the IRS that the rollover to the traditional IRA was completed, should the IRS question the transaction.
