Alexa (echo dot) started playing an audiobook overnight, 3 times, on its own

My echodot started playing an old Audiobook from audible on its own. It did it overnight, several times, full voice. Went to “activity” and it was not triggered by voice (i thought maybe some noise led alexa to think we wanted that). Thoughts?

Thanks!

I would talk to Amazon help. They are usually very good.