2007 Prius - Brake causes a beep

Intermittently, when my foot is on the brake and the car is stopped, the car gives a quiet “beep” that sounds like the horn. My passengers have heard it also. Is there a short somewhere? Could it lead to further problems?

Quiet beep that sounds like the horn? Every car I ever drove with a working horn, it was never quiet. I suspect it is a beeper under the dash, such as a door closed beeper or a fasten seat belt beeper, or a key left in the ignition beeper, that is beeping because of a faulty operating switch, in the door, seatbelt, ignition etc. Most likely you only hear it when stopped because you are not as distracted by traffic and road noise.

Thanks, your answer sounds reasonable. I’ll have the mechanic check the operating switches.