Is it normal for the vacuum pump to leak-down quickly after engine is shut-off or should it hold vacuum on the gauge fairly steady? Vacuum currently reads 25-26 Hg while engine is running, new brakes just professionally installed, lines bled, but brake light comes on while moving down the road, (Did this same thing before break job). Light comes on suddenly then slowly fades out without changing speed. Replace vacuum pump? Gauge temporarily connected directly to pump.