Hi guys

I've been having a problem that might be related to the Master Cylinder on my 2wd Saph Cossie.

When I touch the brake pedal, even if the car is parked, I get a small thump from the pedal. When the car warms up it almost disappears. Also, when I turn the key from cold, the master cylinder takes a long time to build pressure. I can hear it working for 10 seconds or more (it didn't do that for that long). Other than that never had any problem with the brakes and the car brakes fine.

What could be wrong here?

Thanks