My guess? They need more funding to pump out fitbits faster. The flex is about a 6 week back-order to get one right now. Sold out everywhere. Prices is inflated on ebay as well.
If that were the case they should of asked for bank financing. Working capital financing is extremely cheap, and VC equity is at least two orders of magnitude more expensive. Why would anyone want to dilute equity for the company's working capital needs?