Still wondering why Apple COO Tim Cook was wandering around China Mobile HQ earlier this week? Well, it may have something to do with the company’s upcoming iPhone 5.

A worker for China Mobile allegedly revealed on Weibo.com (China’s substitute to Twitter) that Apple’s fifth-generation iPhone will indeed launch in September like previous speculation has suggested — possibly even earlier in the U.S. and other key markets.

Brian White of Ticonderoga Securities issued a note to investors, in which he draws attention to the message posted by the China Mobile worker. The news was relayed by Boy Genius Report after first being published by Chinese language website Bianews.com. Unfortunately, however, neither story goes into any detail regarding the worker’s message, which has since been removed from the micro-blogging site.

As September draws closer, speculation that the iPhone 5 will launch during this month continues to increase, though a report earlier this week claimed the device would launch even sooner in key markets — around the end of August. The fifth-generation iPhone is expected to sport Apple’s dual-core A5 processor, an 8-megapixel camera, and possibly even a dual LED camera flash.