Is it normal for a friend to move without saying goodbye?

A few weeks ago my friend just disappeared from school. At first we thought she was just sick, but after a few days I texted her asking how she was. She never replied. I tried calling to her home, but her parents always replies by "She's out walking" or something similar. ALL the time. She still haven't replied or picked up the phone for me or any of our other friends. She is from the Philippines and was there over the summer, so we think she quit school here and moved, or is moving back. She emptied her locker. Is it normal for her to leave without even saying goodbye? We weren't rude to her or anything.