I have similar suspicions. I never thought of it as traumatic, but when I was very young (maybe 2-3 years old) I was separated from my parents for a few weeks and have to live with other family. I have no memory of the time as I was too young, but in investigating my stutter as I've aged, it appears that was a super stressful and traumatic time for my family and it could've impacted me. For me personally, I dont know what came first - the stutter or the trauma, but I'm very interested if anyone has any studies or articles on the subject.