Your daughter may have a common condition called snapping hip syndrome. It's seen most often in ballet dancers who over train their hip flexor muscles. The tendon flips back and forth over a bump on the bone causing a snap or pop that can be heard and/or felt.
Sometimes this problem occurs in response to true hip joint problems. There could be a hip fracture, tear of the hip cartilage, or fragment of tissue or bone caught inside the joint. Usually this type of problem is much more painful than the tendon snapping over bone.
Ballet dancers seem to have this problem more than any other group of individuals or athletes. They may have hip pain that will only go away when the hip is moved in such a way that a snap or pop occurs. Or they may be pain free but feel and hear the snap whenever the leg is lifted or flexed more than 90 degrees.
It may not be normal, but it is a typical response to the specific activity of repetitive hip flexion.