Systems and methods for determining an occurrence of non-operation shock (NOS) in a disc drive are described. Such determining may be used to determine whether or not the disc drive should be recalibrated or compensated to account for changes induced by NOS. Determining NOS may be based at least in part on a harmonic of the spindle of the disc drive other than the first harmonic, such as a third harmonic of the spindle. In some embodiments, determining NOS may be based on the first harmonic of the spindle and at least one other harmonic of the spindle.