Ken makes a good point.

Many dealers and manufacturers suggest "wetting down" the interior of a new humidor. It does afford a quick break-in period for the humidor....BUT.....

Wetting any unfinished wood surface causes the grain of the wood to become raised. It makes the cell structure expand rapidly causing a rougher surface. While this in itself doesn't really damage the humidor, it may take away the smooth finish of the cedar. But it is also possible that warpage may occur since you are rapidly changing the humidity of the surface of the wood whereas the lower portions remain drier. The wet surface expands while the deeper area remains dry and unchanged. This can cause warpage of the cedar liner.

Again, this one time probably won't hurt anything, but in general it's a good practice to allow a new or dry humidor to humidify slowly. This is best done by simply placing a wet sponge in a dish or on plastic in the humidor and letting the humidor absorb the moisture naturally over the course of about five to seven days.