Brakes Dying??

[comradburk]

I was at a stoplight the other night which was the first time I noticed this potential problem. I had the brake pedal depressed and I heard this small hummm sound (the pump I'm guessing). I could also slightly feel it in the brake pedal (like a small vibration). The noise only lasted like a second or so, so I didn't take much notice. It seems to be happenning much more frequently now though. Does this mean my powermaster is dying? My brake light doesn't come on when I start the car though. I'm pretty new to these cars so I really don't know much about them. Any help is appreciated!