If the report is flagging the questions or instructions from the worksheet itself, there's no need to worry. Your teacher is aware that the worksheet content may trigger the plagiarism detector and will take this into account when grading your assignment. If the report is flagging your own work from a previous submission, rest assured that your teacher is aware of this possibility and will consider it when grading your updated work. Wait for your teacher to review and grade your work before worrying about the plagiarism report.