It's been said above, but my very first thought was adjust the brake pedal switch. 
You can monitor it with VCDS and see just how "hair trigger" the 2 separate sensors are.
I adjusted mine, but it still occasionally does the same thing. Next time I have all the gubbins out of there I'll give it another turn or two.
Sadly that will probably be fairly soon as I have an issue with my DVB-T wiring which is all buried in the same area, behind the drivers knee panel. 
Basically there are two switches in one with very slight difference in the operating position. One works the brakes lights, the other informs the ECUs.
It is very possible to have the pedal released, brake light off, no braking force BUT the ECUs are still being told the brakes are on, with strange sluggish behaviour the result until some minor jolt or vibration regularises everything.
It is of course not a fault, just normal operation, so nothing gets recorded.
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2003 D2 FL S8. Irish Green Pearl/Beige. Solar sunroof, auto-dim mirrors, electric rear seat functions, ski hatch retrofit; extended leather. Aftermarket DVB-T, reversing camera and full XCarlink (Bluetooth etc.).
2016 Volvo V40 T5 Cross Country (4WD) with ALL the toys including adaptive cruise etc. etc. Osmium Grey with Blonde/Charcoal leather interior. Polestar performance "optimisation".  (A much rarer model than a D2 S8 by the way!) Oh, and a brand new engine at just under 30,000 miles on the factory one! 
Finally: gone, but not forgotten.....
1998 D2 PF S8. AgateGrey/Platinum. Every option (I think) except electric rear seats, tiptronic steering wheel, ski hatch, towbar & dimming door mirrors.
e.g. Cruise control, NavPlus/TV, Bose, GSM, Xenons, Solar roof, Parking sensors, Alcantara/leather everywhere of course.  (internal dimming mirror added later)
1998 (very early) Ford Focus 1.8 Zetec; ABS/TCS, Heated screen/mirrors, Aircon, Auto-dim mirror, Leather, Trip computer, Cruise control, OEM Ford SatNav with CD changer.
And before that a lot of Rover 800s, a few oddities, a lovely Triumph Dolomite 1850HL with Overdrive and way back in my schooldays an Austin Seven aka Mini 850!
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