Nah, it's not because she moved. Some schools (read: poor schools) are just excessively incompetent. In middle school, I was somehow assigned two different english classes at the same time. If I showed up for one, I was marked absent for the other and despite me explaining it to both teacher, the office people, and a bunch of staff I got racked up enough absences over the next couple months that my parents were called. It was only then that it was fixed.
Teachers just don't give a damn