STUTTERING (FLUENCY):

Every child, during the normal course of development, goes through a period of stuttering around the age of 2 1/2 -3 years of age.

Stuttering becomes a disorder if the child becomes frustrated and develops other signs such as tension in the face, neck or shoulder area, eye blinks, clenched fists or any other behavioral symptom. If the dysfluency is characterized by addition of syllables, sound prolongations and other clinically relevant errors, there is cause for concern. There are definite differences between "normal developmental stuttering" and a fluency disorder. Please get an evaluaiton if you have any concerns. 

Additional links

Suttering Foundation of America

National Stuttering Association