TurnItIn detects similarity, and similarity is not the same as plagiarism.
Usually high scores where things have been cited properly are not indicative of plagiarism at all. If you get set a piece of work and 50 of the class use the same 5 sources (this can be totally normal and appropriate), then it will flag high similarity.
32% is pretty reliably indivative of a derivative, run-of-the-mill, middling essay, but it is not necessarily indicative of anything else.
There's pretty much no point asking about it before the marks are released. The relevant feedback will come with the marking.