Hi Robert Glazing from the inside?? oookkkkaaayyyy..:-)
Yes, you do need to paint this, although I normally advise this when the glazing is applied to the outside of the window. The purpose is to keep the glazing compound from drying out. DAP 33 is an old reliable compound that has been around for quite some time, and it will stay pliable for some time. Painting will help preserve it. And are you happy with this slightly off-white compound up against your stiles/muntins/rails that are probably a different color?