JERK!, once in a while while driving-Is it the 'traction control, kicking in?

it's usually the jerk behind you tailgating, check your bumper for dents

 

I have not detected similar thing making turn. But once in a while if I hit pothole on one side while gently breaking, tire slip icon lights up and the car momentarily seems to accelerate. Is that what you are talking about? It is to do with traction control, but rather to protect transmission from shock load when the tires grip again. It is a bit unnerving when it happens.

 

It is the part of the "traction control" that attempts to prevent damage to the HSD because of wheel slip. This can happen when you hit a pothole, or go over something where one wheel is traveling a different speed than another.

It is especially pronounced when you are braking with the regenerated brakes and they kick off because of this and you are only using friction brakes. You use the word "jerk" which is actually exactly correct. Not sure if you meant it as such or not. But the derivative of acceleration is a jerk or a jolt officially. When the regenerative brakes kick off your human body feels the jerk (accelerating at a decelerating rate). Humans are good at picking up this feeling but not figuring out what it is or where it comes from.

 

It is a wheel momentarily slipping due to going over something slick and then grabbing traction again.
Traction control or stability control may or may not be involved.

In addition to "person hole covers", the lines painted on the road often are slick too.
Especially when very cold or in the morning when damp.

 

I hate it when one of my wheels slips even the tiniest little bit over a pebble or a reflective paint strip and suddenly I'm lost without the ability to accelerate as a car comes speeding towards me T bone style. Count to three quickly and then acceleration is possible again.

 

yes

 

Your description is brief and vague enough to be kind of a Rorschach blot for every PriusChatter.

If you search the forum for the words friction whoopee you'll be able to read about another possibility for what you might be feeling.