My 12 year old daughter has an uneven waist. she does not have any other symptoms of scoliosis. is this normal?

No: There are a number of possibilities including musculoskeletal abnormalities such as a leg length discrepancy or, as you mentioned, scoliosis; or abdominal causes such as an abdominal mass. It would probably be wise to arrange a medical checkup and discuss with your doctor after a thorough examination.

Odd question: There are no "symptoms" of mild to moderate scoliosis. It is a physical change that gradually appears over time and is unnoticed unless looked for. Proper full spine xrays are my minimal evaluation tool when I suspect it.