Yeah, check to see if you have some broken plastic pieces on your floorboard. I had the same issue, and found my grommet broke. You can just take some metal washers, pennies, or other small round coins/metal objects and duct tape those bitches around the brake pedal lever. That's what I did and it's worked great since. A little tricky at first, trying to do it yourself...but not that bad.

If you lay down on the floorboard, you'll see where the grommet should be on the brake pedal lever. When the brake pedal lever is in it's neutral position, you'll see where it should be contacting the brake light switch (little black button thingy), towards the top of the brake pedal lever. Snugly tape down some coins/washers, etc. in that spot....then test it by pumping the pedal a few times, or take it out for a small spin.

Be sure to check on it for the next couple days as well, to make sure the tape holds up. As long as you have the tape wrapped tightly, you should be good to go. Just make sure the tape cures over the next few days and holds. Voila! Problem solved.