Hermione realised the magic had come to her twice now, in the times she needed it most. Consequences be damned, she had used the Blood Magic to rescue him and by extension, herself. There would likely be an investigation, but this type of magic functioned in surreptitious ways. None of the students had paid Hermione or Malfoy any attention outside. It had placed them in a bubble; there were no witnesses and no spell to track. 