2013 Ford Focus transmission issues?

I got my 2013 Ford Focus SE (hatchback) about 3 weeks ago. I unfortunately got rear-ended a day after purchasing the car. After the accident I noticed my transmission would jerk/hesitate/shudder when taking off from a complete stop. It wasn't doing that before the accident at all. I see online that many other people are having this same exact problem.

My questions to anyone who's experienced this is:
Have you gotten it fixed?
After getting it "fixed" did the problem completely go away, get worse, or stay the same?
Is there a way to get it taken care of free of charge?
(I have it under a 30-day warranty with carmax but I'm not completely sure how they work when it comes to something like this)

Any advice/information helps. If it's fixable and people have had success with having the problem cleared up I d love to keep the car but if all else fails might have to do the whole Lemom-Law thing.

Broken trans mount, have it check

Its up to the insurance co to fix as it was caused by the wreck. Make sure the insurance adjuster knows its messed up because of the accident.

I would have the motor mounts checked.