OCR changing look of document

[laura_4187]

I OCR all of my documents and I haven't really noticed this issue until today. After the OCR is run, I do not look at the results, so there's no overlay on. The PDF should essentially look the same as before the OCR process. However, there are these gray bars on top of a couple of lines that do not have text. Why do these appear? What else is it altering? Picture attached.