Misdee I know that some children with autistic disorders flap their hands alot and it seems to carry on through life, having said that my DD used to flap her hands from around 1-2 yrs until she had enough language to express what she wanted so i guess it has to be within the context of how your dd is in all other aspects!! Hope that hasn't made you worry!!
My DS3 has dyspraxia and used to flap his hands.
DS5 has just been diagnosed with Aspergers and flaps his hands a lot, when he is excited or tired. It was the first thing that concerned me about him (because I knew from DS3 that flapping can indicate a problem) and I mentioned it the the HV at his 3 year check. That is when he was referred to the child development clinic.
My DS5 also has other "stims"-he jumps up and down on the spot; runs back and forth to the same spots; and spins around. Does your DD have any other of these behaviours?
Ds1 used to do a lot of handflapping when he was frustrated, excited or just didn't know how to say what he wanted. He used to flap so hard that he looked ready to take off. He only tends to do this now when he's tired or over-excited.
Ds2 (2.2yrs) is going through the 'flapping baby bird' stage now. He usually does it when he's excited or can't say what he wants.
It's definitely worth mentioning even if it turns out later to be irrelevant.
My ds aged 5 has ASD. He's never really hand flapped much at all, but like Tiggiwinkle he also runs back to the same spot, in fact he seems to be able to express himself better when he's running around. Also when he's talking he will often write out letters in the air with his finger. Strange eh??
My Daughter is 8, when she is excited she 'flaps' she will jump up and down on the spot and flap her hands, we think she is dyspraxic, (long story)... I didn't know this was a trait of dyspraxic children though.
I would mention it. Also look for tip-toe walking, head shaking, looking at things from side of eyes, bringing objects right up to eyes, jumping, spinning etc. Any sort of strange body posture, eye behaviour, hand positions. Although many of these behaviours occur in NT children they move on and they could just be part of development. With children with ASD they do them for longer at a time and for longer overall iyswim. My DS didn't hand flap until about 2 years ago (he's 9.5 now) but he is the world expert on it now!
With my 2 boys the toe-walking seemed to depend on what surface they were walking on. Ds1 used to tiptoe a lot on concrete (even with shoes on). Ds2 toe-walks on surfaces he is unsure of. Some surfaces he won't walk on at all.