My personal experience would be "No, you don't need a transit visa" There are apparently some cases where you do: they have to do with how long your layover is (mine was 8 hours) and whether or not you have to change terminals (I did not)
At least, that's what Aeroflot told me when I had the same question. The airline was quick to remind me -after explaining why I didn't need a transit visa- that I really should check with the Russian consulate, as "government policy" and "airline policy" can be out of sync sometimes. But I never did get an answer from the consulate.
That was gonna be my story if it had become an issue at the airport. But nobody seemed to care about transit visas at all.
So having said that, I'm gonna be like Aeroflot and remind you to check with the Russian consulate ))))