There is something about starting new jobs or going through major life transitions that can cause a resurgence of stuttering in some people. I’ve experienced this myself whenever my career has taken a big new turn (new role, new colleagues, new location, etc), but it always normalizes after enough time goes by and the day-to-day interactions get somewhat predictable again. It ultimately boils down to a person’s sense of comfort and familiarity, I think. Don’t despair. It will pass.