Happened to me in the past. A new job or new anything gets you reved up and energized. You tend to have tons of energy when things are new and it helps me keep on top of it but then when things get to be routine your focus is different and you can't possibly keep that intensity level going so like all stutters who get tired it gets worse. Stuttering in general is so volatile anyways. So many ups and down periods even in just one day. Just know that and be kind to yourself if all possible.