"all of a sudden" is definitely a standard idiom. In fact: https://trends.google.com/trends/explore?geo=US&q=%22all%20of%20a%20sudden%22,%22all%20a%20sudden%22

"all of a sudden" is definitely a standard idiom. In fact: https://trends.google.com/trends/explore?geo=US&q=%22all%20of%20a%20sudden%22,%22all%20a%20sudden%22 https://trends.google.com/trends/explore?geo=US&q=%22all%20o...