Transmission Pan Gasket Question.

I had a new transmission pan gasket installed on a C6 transmission, the bolts were torqued the right way, to 10 foot pounds, like the gasket manufacturer recommended, but it is still leaking slowly at the pan, the car has a large one quart transmission cooler, installed in front of the radiator, the fluid lines from the radiator to the trans cooler add another one third of a quart or slightly more to the total transmission fluid capacity in the system, which is almost one and a half quarts more than it came with from the factory, so when the car is parked facing uphill the fluid leaks very slowly from the back of the pan, when the car is parked facing down hill the fluid drips very slowly from the front of the pan, it is a thin cork style gasket, that came with a new filter, i saw a picture in a book where it shows a transmissions fluid is slightly lower than the gasket area when the transmission is on level ground, but if you park a car on a steep hill, the fluid should not leak at all, the gasket surfaces on the trans and pan are clean and flat, so that is not the problem, do i need a thicker gasket or a larger capacity pan? 

Did you tap the bolt holes like I said in the other thread?

The pan is flat and straight all the way around the mating surface, it is not bent, the gasket does not look squished, i did not use any sealer, the bolt holes are not deformed, it was torqued with a torque wrench, i am sure the leak is from the pan, the gasket is a little over one sixteenth inch thick, i dont think this pan has the ridge on the mating surface.

Since you did not recomend a larger capacity pan, i too think the problem is the gasket.