There have been lots of reports of Alexa speaking out when not prompted, but this incident is a "first" after having an Echo for over two years . . .
Echo is playing a classical Tunein station. Right as the next track of music begins, the Echo's Alexa responded to its own speaker and said, "I didn't understand the question I heard." Not so unusual except it responded to its own speaker! I checked the history of what it heard, and it showed "forty two". I then listened to what it heard/recorded, it was the radio announcer saying, "Next up is from the Easter Contada from JS Bach; his Contada Forty Two, is the symphonia"
Now, this was a lot more than hearing/recording forty two, and then to react to it??? I am going to reboot the Echo, and hope this was a one time event!