I reversed into parking spot at work,i hit the brake, lifted the handbrake, and a red light began to flash at bleep on my DIS. It's an '!' mark in a circle with brackets around it. Colour of the light was red. It flashes 3 times and bleeps 3 times with it. I drove 20 mins to work and when i hit the brake it was fine. I tested it in the car park and it only happens when i reverse and lift the handbrake?? Any ideas?? PS. i had all my brakes changed with fluid about 3 weeks ago.