M B wrote:

But WHEN I did it, I think the surprise of
looking at an ASI and having it tell me...
ambiguous garbage...

I find it even more surprizing that somebody in this situation would
look at the ASI at all...

I tried spins later with further aft CG and was able
to
sustain spins, with the expected noise and control
feel
indications.

See? You *can* tell a spin from a dive if you have familiarisized (?)
yourself with the glider. Which you should (must, according to the
legislation where I live and fly) in your first couple of flights, anyway.

Stefan