I believe this used to be one of the "MBD" signs people looked for back
when MBD (minimal brain damage) was a fashionable diagnosis.  I have no
idea what the validity of this sign is.

However, it now occurs to me that various motoric oddities, including
oddities of gait have been decribed as an early expression of autism
--paper in the Proceedings of the National Academy of Sciences; I can
date it as probably sometime in November, because I recall asking
Isabelle Rapin (autistic spectrum maven) about it at the ARNMD meeting
in early December, but cannot give a more precise citation.

It should be noted that various kinds of neurological and
mechanical/orthopedic sorts of problems might cause disordered gait, so
do not diagnosis anything simply on basis of this tip-toeing, but use
it to suggest directions for further diagnostic efforts--i.e. examine
to "rule out" neurological motoric problems, "rule out" autism, etc.

You may safely infer that I do not take the picturesque interpretattion
you heard very seriously.

F. Frank LeFever, Ph.D.
New York Neuropsychology Group