We've been having a problem with one of our cars for a little while now. Nothing serious, just an annoying light (BRAKE!) that pops on and stays on about every other time the car is driven. So, yes. Not a big problem (we hoped) but still slightly worrisome. Also, the car's manual says that you need to have the car checked right away if this happens.
We had this problem once before when we were driving through a nasty storm and our car was hit by lightning (that was a fun experience), and the light came on and stayed on. Since we knew the cause we weren't too worried about the problem, and it was fixed by some guy at the shop resetting some switch and sending us on our merry way.
This time we didn't know the cause, and as the light started coming on with greater frequency, we started to worry that maybe there really was something wrong with the brakes. This is the car that I had the major front end collision in, so we're always a little worried that it's going to fall apart on us.
Anyway, (I've dragged this on for much longer than the story is interesting; sorry) Aaron finally got worried enough to take the car into the shop this morning. He got there, they topped off the brake fluid, and sent him on his merry way. This was incredibly embarrassing for him, a car guy who couldn't figure out what was wrong when he looked. Glad we spent that money!