College in the U.S. is usually completed in four years; however, at many colleges in CA, students can't get their classes because of overcrowding and are forced to take extra semesters. Also, if you change your major, that puts you behind, or if you pick up a second major. My 23-yr old son graduated from college last year, but many, many of his friends JUST graduated, taking the five-yr plan. Looks like ML will graduate in 5+, so maybe she changed majors, failed a class or two, picked up a second major or minor that required more classes, etc. It's not uncommon here at all.
The University of Utah also has the lowest 4 year graduation rate in the PAC12 (their athletic conference). Somewhere I read a list of MLs studies and they seem really intense. I can certainly see taking summer classes and an extra year to finish.