4 yr old crying while asleep what does it mean?

We were just in a car accident in my causin's van about 4 days ago. My daughter along with my other two kids and my causin's 2 daughters we are all fine thank God. For the past 4 nights my 4 yr old has been crying in her sleep through out the night and early mornings. I don't wake her up because I am afraid she will freak out. What does this mean. When I spoke to her dad on the phone just a few minutes ago? He is a local truck driver, and she told me to tell him "Tell him Not to crash like my aunt Veronica?" What can I do?