No, it was more like the final straw that set all of the events in motion. It started with the Taiwanese matter that mainland China took advantage of to assert control. Mainland has been actively working to integrate Hong Kong into China for quite some time now both on the cultural side by encouraging Chinese to move to Hong Kong, and on the political side by removing complete authority away from Hong Kong. If you have ever visited both places you can easily see that they are 2 separate cultures. Hong Kong does not want to be China, they want to govern themselves. This is what these issues are about. China is increasingly trying to assert control while Hong Kong wants to be sovereign.