New iPhones came out! 10 Million people bought a new iPhone in the first weekend! Wow, we must have sold a ton of apps.
Here's a graph of three months worth of sales, including September 19th. They weren't bad days when the new iPhones came out, but they don't stand out in the chart at all. Just a regular old slightly better than average day (preceded by 3 worse than average days.)
10 million new iPhones, everyone using their shiny new devices. Negligible app sales. WTF.