Million Dollar Mistake?

Here is an excerpt from an article in the current issue of Fortune Magazine. Can anyone guess what the million dollar mistake Sheryl Sandberg made was?

Take the case of Sheryl Sandberg, a 37-year-old vice president whose fiefdom includes the company's automated advertising system. Sandberg recently committed an error that cost Google several million dollars -- "Bad decision, moved too quickly, no controls in place, wasted some money," is all she'll say about it -- and when she realized the magnitude of her mistake, she walked across the street to inform Larry Page, Google's co-founder and unofficial thought leader. "God, I feel really bad about this," Sandberg told Page, who accepted her apology. But as she turned to leave, Page said something that surprised her. "I'm so glad you made this mistake," he said. "Because I want to run a company where we are moving too quickly and doing too much, not being too cautious and doing too little. If we don't have any of these mistakes, we're just not taking enough risk."

If you need a hint please read this previous post: Retired and Back.