No. Stuttering can hit people at any time. Some don't get a stutter until they are in their teens or even later. Some stutter for a few years in their childhood and then it goes away after a few years. Your son starting to stutter now even though he's been speaking more fluently is not out of the ordinary in any way shape or form. It's very common. I have to echo the above concern about your over-concern about this. My families negative reaction to my stutter in my childhood actually made things much, much worse than it should have been. You need to remember that a big factor in stuttering is psychological. A kid who feels under stress to perform will struggle to speak fluently and then beat himself up when he fails. This creates a terrible feedback loop where he comes under increasing stress to speak, to please you, only to seize up with tension and fear when he can't get the words out. This creates a cycle of self loathing, withdrawal from speaking and socialising. And a great deal of this will be caused by your negative reaction. That's right: you are making your sons stutter worse. Ideally, you would outwardly show you son that stuttering is no big deal. It happens to a lot of kids. Roll with it. You will love your son and support him no matter what. Yes, behind the scenes seek speech therapy but even then, treat it like it's no big deal. You freaking out about to the point where you are losing sleep will not be lost on your son. He will sense your disappointment in him. He will feel like he's a freak or a leper because he trips on a few syllables. This will make things, much much worse. Perhaps you might want to see someone yourself about setting too high expectations on your kid and to explore why that is.