When mam passed away a week ago today, after she died she started crying. I cannot get this out of my head. I was wondering what this means?

I am so sorry you were disturbed by this. As JoAnn said, this is not unusual. Many things happen after death to our bodies. Nurses become used to it. Some religions do not believe in disturbing a body for 24 hours and will sit vigil during that time; they are also more used to things that happen.
You will often hear people say that their elder looked younger, almost beautiful shortly after death. And this as well is normal with muscle changes.
Please don't be disturbed. And am so sorry for your loss. What helped me a lot after the passing of a much loved bro is to write him letters, make a scrapbook of collage of things he loved, places, things I thought to tell him. I am not a believer, but this magical thinking helped me to get through, and to celebrate him more than mourn him.
Hugs.

This may happen when muscles relax. May have been tears in the tear duct and released when the muscles relax.

I am so sorry for your loss.

May God give you grieving mercies and strength during this difficult time.