94 villager brake fluid issue

[tempfixit]

94 Villager 177,000 miles.

The master clyinder reservoir was empty of fluid today. I replace front pads earlier this spring, as the pads wear I have always had to add fluid. I checked everything this past weekend and the fluid was between the Max and Min level. Putting the vehicle and ramps I looked for any leakage on all the lines, master clyinder, front calipers and rear clyinders everything is dry.
I had a friend pump the brake pedal and noticed that the master clyinder moves back and forth at the power brake booster, is this normal? Any ideas why the fluid disappeared so fast would be greatly appreciated. Meanwhile I am going to drive and watch the fluid level.

Thanks for all advice.

[dzus]

The M/C will move with the booster a little. Did you look above the brake pedal where it comes thru the firewall for leaks?

[tempfixit]

I did look under the dash where rod comes out of booster and it was also dry.