Parking brake light goes on and off while driving
 

This problem started about a month ago. I live in San Diego, CA and I generally park on a hill. I always use my parking brake when on the hill. Then one day the brake light stayed on but I did not feel anything like that the brake was still engaged. As I started to drive, the light went off but then randomly it comes back on while driving. Pretty sure it's just an electrical issue since I know mechanically the parking brake still works and the brake fluid is full. Just trying to figure out what it is. Thanks for your help.

Parking brake switch under the pedal.