the drain hose from the cabinet to the drain pan is not aligned correctly
it is either dead center and dribbling through the pan(there is a slit in the center of the drain pan where water can pass through)
or the hose is positioned so water is going into the shallow resevoir of the drain pan(it has a deep side and a shallow side)
reason you might not have seen the leak.... the pan will overflow during periods of high humidity from a combination of the hose draining into the wrong chamber of the pan, and those drain pans dont fit tightly and have little thermal paste so the water does not evaporate fast enough
first few i saw when the new drain pan came out drove me nuts till i figured it out