That's some shady behavior though. The whole point of the law is to prevent companies from penalizing employees based on prior salaries. Wouldn't be surprising if Google was finding excuses to retract offers based on seeing that they "overbid" on someone's comp. If anyone has had suspicious stuff like this happen, it sounds like it'd make a great lawsuit.
Would be nice if some journalist(s) made a big stink out of Google finding a loophole in this employee protection law.