2012 R1200RT front brake reservoir gasket problems

Having reoccurring problems with the urine cup front brake reservoir gasket being deformed and need some advice on if "they all do that" and I just have to deal with it, or it is just my bike and repairs are needed.

Very often in the summer, the gasket is deformed down into the brake fluid. I then remove the cover, wipe DOT 4 brake fluid off gasket and cap, then reinstall. Seems to be good for a few days / weeks, then happens again. Brakes feel a bit mushy before gasket cleaning / bleeding, and much better after.

Bike is parked out in the sun at work and all the black parts get nice and warm. Have been replacing the gasket about once a year. Bleed brakes about twice a year. There are 2 small slots cast into the cap and they are open and clean. Screws are fastened down by hand using T20 torx screw driver. Have used BMW fluid, auto store fluid, currently using Amsoil DOT 3/4.

Cannot tell if there is air pressure pushing the gasket down? or if there is a vacuum sucking the gasket down?

Thanks in advance.

Not sure on your bike. My experience has been the gasket expands/droops/settles into the brake fluid to keep the "sloshing" down and reduce the atmospheric exposure of the ambient air to cut down on the hydroscopic nature of brake fluid.
I wouldn't be worried unless the fluid starts to escape from under the cap.
OM

I agree with Gary's comment. You are probably doing more harm to the brake fluid by repeatedly opening the reservoir and exposing it to the humid Virginia air.

It's suppose to do that. As pads wear, brake fluid level drops. Since the brake system is air tight, the vacuum from the fluid level dropping pulls on the flexible gasket. I have seen this on other vehicles.

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Mine deformed like that and would no longer sit properly and seal. I tried to "retrain" it to the correct shape but that didn't work. So I just bought a new one. Problem solved. Yes, the price was stupid $$$.