Question about humidifier

When I turn on the humidifier, the hose going in to it blows the water around like waves. As soon as I put the mask on, the water stops blowing around. I just noticed this and was wondering if this means the humidifier is not working properly. I called my dme and they could not give me an answer.

With mask off, the blower unit is blowing air at maximum capacity cuz it cannot maintain set pressure ... makes waves on water surface.

With mask on, blower unit is only blowing air sufficient to maintain set pressure (basically, air velocity andvolume is same as your normal breathing) ... water stops blowing around.