Why the long wait for my package to clear Chinese customs?

I placed an order December 21, 2015. The seller provided me a tracking number #LS411375827CN (China EMS) on January 15, 2016. The package arrived at Chinese customs on January 19, 2016 and this is the last update I received. I explained to the seller today, January 30th that I would be filing a dispute through my credit card company if he did not investigate as to why I am still waiting for delivery.

I have since placed two more orders on January 18, 2016 from another business in China and have received both today, January 30, 2016!

Should I continue to wait patiently, or file a dispute with my credit card company?