Hello goericgo, thanks for your question.
How clear do you think it is to the admissions committees that the position was a temp one? If you went as far as to mention that a staffing agency placed you, then I would think any normal reviewer would understand the situation, right? Also, if you had a long tenure in that role, then perhaps the fact that you were a temp matters less?
I would write a follow-up email only if I thought that I gave the adcoms the wrong idea of the work.
I hope this helps.
Best of luck,
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