What Causes Baby To Experience Twitching In Muscles?

my 8 month old son had been exhibiting some strange muscle twitches, mostly at the end of his feeding. His right shoulder goes up to his ear and his are extends in front of him for 2 - 3 seconds. he doesn t cry, he continues to eat, and he doesn t stare into space . I am waiting for his pedi to ring me back. Can this be something other than infantile spasms? this happens maybe 2-3 times a day.