I haven't been on in soooo long sorry about the late response. My 3 year old DD has PDD-NOS and is on the "spectrum". When we first started noticing things were "off", one of the things she was doing was walking on her tippy toes - which can be a sensory issue (she has many of) or a a PT issue (which she also has many of). My 1 year old DD has started walking on her toes a lot and it makes me nervous, given the issues with my other DD. It is just something to watch, and I keep a close eye on things.