Nevermind that, if they could access the device, they'd also be able to read your kvm i/o.
That said, the microphone is so weirdly positioned that it gets suspicious indeed.
How is it weirdly positioned? To me it seems there is rather few options for such small board.
If you are too lazy to go back and check if you left the gas on, you bear responsibility if the place explodes.
At the very least, it's negligent to leave something like that in and not be very upfront about it.