Driving home today, daylight, dry road, on a bend to the right in the two lane country road the car suddenly and for no reason that I could see swerved to the left into the left lane and was half way into the left lane before I could recover. There was no oncoming traffic (it is not a blind curve so I could see there was no oncoming traffic). I was driving at the posted speed limit (40 mph) (the car had slowed slightly before entering the curve ). What made this difficult to recover from, I believe, was that the car had entered the right turn (curve) which caused me to relax pressure on the wheel (allowing the steering wheel to slip through my hands) and then suddenly went to the centered position which caused the swerve to the left, this made this movement very rapid like a coiled spring (the steering wheel to the right then suddenly straight very close to the centerline of the roadway) . I have driven this road many times and the car has in the past gone over the yellow line making this same curve but has never swerved dramatically to the left. I have never seen this on any other right turn for the year I have be using FSD.