brake problems..(warning light)

alright. any idea how i'd know if it did have an internal leak? because if you hold the pedal at a certain point, the pedal will "loose pressure" meaning my foot will just keep going down.

You just answered your own question. Its the master cylinder. Or a slight possiblilty like longgone has said. But a leak should be very visible if it is leaking/loosing pressure that fast.