You are very naive if you think that Google does something by mistake (that also happens to fit well into their Big Black Hole of Information).
Nonetheless, I doubt I'm naive to believe engineers are not always making mistakes. The trick is always in admitting mistake, learning from them, and fixing the future. In this case, Google acknowledged the -- lawful -- slip in privacy encroachments and assigned a privacy director to oversee engineering and product management efforts. Every Google product now maintains a privacy-design document.
Almost certainly it is, but would I be surprised if it were true? Would anyone be?
I'd be willing to bet the NSA had a good browse of the resulting data, either way.