force 320

Went to Havasu for 4 days last weekend and every morning at the dock, checking fluids, I was losing about 1/4 qt. of tranny fluid in the port tranny, no visable signs of a leak while idling but fluid was in the bilge. Got home ,cleaned everything, ran it on the hose and no leak. what the hey? the top of the tranny was a little wet around the vent on the lake , could I be pumping it out the vent at full throttle? 496HOS-Velvet Drive Trannys. Thanks All.