Aside from the other conversation about anxiety, life changes can cause changes in "how" you stutter (frequency, severity, etc.). I'm an SLP who works with adults and a lot of people who contact me are recent college grads who have found that their stutter has suddenly changed (usually increased) since they started working, moved to a new location after graduating, etc. Even if the changes are positive, any life change can serve as a catalyst to impact your speech.