> I asked if I could call back a phone number listed on Google.com and she said sure - this number is listed on google.com and you can call back with your case number, but there may be a wait on hold and I might get a different agent. I googled it and sure enough, it was listed on google.com pages. I didn't call back though.

Emphasis mine.

Also, if a human called me and claimed to be working for Google, I would laugh heartily and hang up the phone. Google doesn’t even have call in tech support, why would they call you for something as banal as a compromised account?