True, but it's still scary how the phone seems to be able to reverse lookup my email address to come up with the matching Google account. Which, I might add, originally started out as a YouTube account.

Considering how much Google tracks, I find it hard to believe they wouldn't save that mapping somewhere besides my friend's phone because this is exactly the kind of data aggregation and mapping which is driving large parts of Google's ad business.

I admit this might just be paranoia, tho this wouldn't be the first time my paranoia ended up being justified.

Android offers to sync your contacts to the cloud/between devices. I think its still opt-in, but could be different on other devices than I've had.