Stuttering is very common in little ones. My four year old will sometimes get overly excited and stutter, but it was a lot more common between 2 and 3. He had poor pronunciation, and we worked with him to properly pronounce "oil pump." That worked, until he saw one. Then he was just so excited the only thing that would come out was "opapa! opapa! opapa!"
Don't worry about for a few years. Stuttering in adults is quite psychological (worse under nerves), so the general advice for very young stutterers is not to call attention to it at all, positive or negative.
