Asked by Labour education spokesman Chris Hipkins why she did not act sooner, Ms Parata said: "Because the focus has been on fixing it."
Around half of the exam papers were recovered immediately, and NZQA was working on recovering another 180.
Ms Parata said she did not feel NZQA had handled the mistake as quickly it could have.
In future, students could be able to obtain both a digital and physical version of their exam booklets. This option was already available to scholarship students.
Mr Hipkins was concerned that students would not be able to seek reconsideration of their results if they did not have a copy of their papers.
The minister confirmed two students affected by the mailing error had sought a recount.
"For any other student that might be affected, recounts are available to them by engaging with their school in the provision of other work that the students may have completed."