A week ago, we learned that there is in fact a microphone Google included with its Nest Secure home security system that the tech giant says it forgot was there and thus forgot to tell anyone about. You could argue there are serious privacy implications inherent in a slip-up like that, which is precisely why a few US senators have now sent a letter to Google CEO Sundar Pichai asking him to explain himself.

“In recent years,” Senators Roger Wicker, John Thune and Jerry Moran write, “consumers have become increasingly concerned about the ability of large technology companies to collect and use personal data about them without their knowledge. Therefore, it is critically important that companies like Google be completely transparent with consumers, and provide full disclosure of all technical specifications of their products at the point of sale.”

Last September, the letter continues, Google’s chief privacy officer testified during a US Senate Committee hearing that transparency “is a core value” at Google. “That is why Google’s failure to disclose a microphone within its Nest Secure product raises serious questions about its commitment to consumer transparency and disclosure,” the letter to Pichai notes.

It goes on to ask Google’s top executive to respond in writing by March 12 to a series of questions — and to provide “an in-person briefing” to Congressional staffers by March 29. The questions are pretty much what you’d expect them to ask, like whether the microphone has indeed always been there, as well as when and how Google became aware it wasn’t included in the technical specifications that were spelled out to consumers.

The Senators also want to know how Google has communicated with users about this issue, whether it’s aware of any third party using the microphone capability for unauthorized purposes and if Google is aware of similar omissions in the listed specs for any other Google products. Also, Pichai is asked to “describe Google’s process for developing technical specifications for its products. At what stage of the process did this error take place that resulted in the omission of the microphone’s presence in the Nest Secure device?”

As we mentioned last week, Google has already released a pretty bare-bones mea culpa about this, sharing a statement with Business Insider that says the mike was never meant to be a secret and should have been included in the tech specs. “That was an error on our part.” The company went on to explain that “the microphone has never been on and is only activated when users specifically enable the option.”

The long and short of this is that if you bought Nest’s $500 home security system, which is only a year old, you’re just now learning that you’ve inadvertently had a microphone in your home for a year or more that you didn’t know was there. The ball is now in Google’s court to respond to the questions raised in the Senators’ letter, which you can read in full here.