I'd say so, but might be hard to pin point the cause. My speech is decidedly worse when I am anxious and stressed - I developed new blocks thanks to Covid/losing my job. At 3.5 I can imagine it's hard to pin point what is a stressor but I am not a parent. You know your child best. Some folks report their stuttering is worse or milder when they're tired for example. Perhaps you should note down days when she struggles, and what was going on the day before, or even the week before and see if there is a stressor? I'm glad you're getting her help! It sounds like you're doing the right things by letting her finish. I actually have instructed my close friends to start filling in words for me recently because of the particular block I developed recently. Once I hear the word, or if I have a 'lead in word', I can say it. But they know to only do this when I asked or indicate. Stutterer or not, she'll go far with supportive parents like you. :)