While overtaking a stationary bus and giving it plenty of room there was a sudden grinding noise. It felt as if the ABS system was kicking in and despite under acceleration the van slowed down. A tone sounded from the dash and a graphic came up for a few seconds only. This looked like a roadway with with a set of broken lines on either side. In between the lines the number 40 appeared ! The incident was over in seconds and the van continued to accelerate to pass the bus. I have experienced ABS kick in before on other vehicles but never in perfect dry weather and whilst accelerating ! Is this a problem with the front radar or just a glitch ? Has anyone else experienced anything similar ? Thanks......Wolfie.