It appears like a random yet welll executed attack ..
Reading a lot of the google forums it's happening frequently with google checkout users ... Google claimed my account was compromised on the 1st Aug .. the attacker didn't do anything until the 6th ... just letting the dust settle . My guess is they do this on a regular basis .. with any luck they'll be caught soon and get whats coming to them ..
I'd love to give them a piece of my mind , I know that for sure