Sources close to Groupon, the social-buying site, said its president and COO, former Yahoo exec Rob Solomon, is stepping down from his job.

It's not clear what the reasons for Solomon's departure are, but the move seems to be sudden. It is also unusual given the fast-track trajectory of Groupon, which is currently considering at IPO at gigantic badillion-dollar valuations.

Nonetheless, CEO Andrew Mason just sent out a short email to staff about the move. BoomTown had sent him a query earlier today about the inquiring about the possibility of Solomon's leaving.

In the e-mail, sources said, Mason said Solomon was moving back to "'God's Country' in Woodside, CA" from Chicago, where Groupon is headquartered.

Mason praised Solomon for his work in the lightning growth of the start-up and noted "he will remain a friend and advisor to the company into perpetuity."

Apparently, though, from faraway seat in God's Country in Silicon Valley.

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