The problem with getting hit by a car the first time is that it could have easily been your last time. Sometimes one is just so happy to be alive and walking afterwards, that the details don't matter. In your case, with a leg bruise like that, it could get complicated. Compartment Syndrome leading to other damage, or the hematoma just does not go away and may need to be taken care of.

If you go through the motions at the scene and collect all data and get a police report (you were hurt, just not badly), you will be in a better position if things go sour later. If not, then toss it in can and live on.