What should you do if you find a few sentences of verbatim plagiarism in the literature review of published PhD thesis? I am a Ph.D. candidate. Here I have a question, and I really want to hear what you would suggest.

Recently I did some literature studies, and I read a researcher's Ph.D. dissertation. She is kinda a pioneer in my research area, therefore I read her dissertation really carefully. However, I found that in the literature review chapter of her dissertation, there are parts of verbatim plagiarism. They are not blatant paragraph-to-paragraph copy and paste. They are just around four or five sentences, which are directly copied from other journals.  

Her dissertation is around 300 pages with 8 chapters. I would say this dissertation is a high-quality dissertation. Besides these two tiny parts that are susceptible to plagiarism, it is really perfect.

I just wonder: what would you guys do? From my side, I don't want to report this to anybody at all, because I believe this might just an innocent mistake or something like that. Honestly, these two parts of verbatim plagiarism may account even less than 0.0001% of that dissertation.
A few sentences copied out of the papers reviewed in the literature overview before the main text of the thesis? I'd be rather surprised if that doesn't happen all the time.