The best possibility I can think of for the LS-6 is that something
(certainly not winter clothing at Narromine, this time of year) was
pushing outward on the flap handle to prevent it from latching into
the ratchet track.

I once experienced strange behavior during take off in a glider I had a few
hundred hours in. The trim lever was caught and moved to its back stop by
the band of my wrist watch. I felt something tear on my wrist, a little
later during take off I realized that the trim was completely wrong, but it
took me some time to understand what really happened ...

Michael