Yeah, pretty much. It's likely that the device heard something like "Alexa, send a note to Enrique" and then recorded and sent the subsequent note to the matching contact that it found. The microfailure is that it either failed to respond to the user in a way that was clear, or did it in a way that the user didn't notice (I dunno, volume all the way down? Output to a bluetooth speaker or headphone jack that wasn't audible?). And that can be fixed.

The macrofailure, though, is that you have a device just guessing at what you want and doing it. That can't be fixed without going back to manually constructed (or at least manually triggered) notifications. Which for "send a note" might be an obvious fix, sure, but there is a lot of gray area in what constitutes "privacy" and Alexa would be pretty useless if you had to affirmatively OK everything it did.