  KIC 3429637 (HD 178875) is a delta Sct star whose light-curve shows
continuous pulsational amplitude growth in Kepler Mission photometry. Analysis
of the three largest amplitude peaks in the Fourier transform indicates
different growth rates for all three. We have ruled out instrumental causes,
and determine the amplitude growth to be intrinsic to the star. We calculate
time-dependent convection models and compare them with the observations. We
confirm earlier characterisations that KIC 3429637 is a marginal Am star
through the analysis of new spectroscopic data. With the data presently
available, a plausible cause of the amplitude growth is increasing pulsational
driving as evolutionary changes shift the He II driving zone deeper in this rho
Puppis star. If this model is correct, then we are watching real-time stellar
evolutionary changes.
