Should I retake the GRE

[HarryMing]

I'm an international student from China who recently graduated from UCLA with a 3.5 overall GPA, and a 3.8 statistics major GPA, and am going to start my statistics master's program at Columbia University this Fall.

I plan on applying to a PhD's program in statistics after I graduate from Columbia but I don't know if I should retake my GRE

I have a 170 (98%) on Math, 163 (92%) on Reading, and a 4 (56%) on writing. I am preparing for my GRE Math subject test but I don't know if I should retake my general GRE because I only got a 4 on writing. My dream schools are: 

Stanford
Berkeley
Chicago
Harvard
Washington
Columbia University

Since those are all competitive universities to get into for a PhD in statistics, I'm conflicted because I don't know how much getting a 4 on my writing matters?

I really appreciate every advice. Thank you all in advance.