That was most likely caused by the FCW forward collision warning.
It's the button below the radio controls near the Eco button.
Very helpful in general if you're dreamy while driving
It only happened to me once for it to go off with no app obstacle In front. On the highway where it displayed the brake message and only mildly applied the brakes.
I only had the thing brake like crazy once...couple of days ago. Had a car in front the stepped on the brakes but it was far enough for me not to worry...I was about to brake too when the fcw displayed brake and braked like crazy. I wasn't wearing the seetbelt so I hit my head on visor. First time when I said bad words to my Jeepa.
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