Risk of Plagiarism for SOP, Help Needed

[beeshirp]

This is an embarrassing question and I will be as honest as I can. After I wrote my SOP, I asked a senior friend who graduated two years ago to help me edit it. She made some structural changes and a hook sentence at the beginning. I liked the changes, so I kept them in the submitted version. However, I talked with that friend yesterday, and was told that that hook sentence actually came from her SOP when she applied to graduate schools. Everything else in my statement, except for this sentence, is original. The more I thought about it, the more worried I got. I feel horrible for the mistake and am worried that this sentence would ruin my applications

So, the question I have is, whether graduate schools would run some kind of plagiarism checker on SOPs, and what I should do given that the programs I applied to don't allow updating materials.

Edited December 4, 2021 by beeshirp