I had a similar event about a month ago, towing a newly soloed young
pilot in a 2-33. He had requested a pattern tow, so approaching 1000'
agl I was expecting a release - instead felt the tail of my Pawnee
yanked up about 15 degrees, followed by the obvious release by the
glider (while I was reaching for my release!).

After we landed I mentioned to the young pilot that his release had
been a "bit unusual". His answer was that he had been taught to do
soft releases by his primary instructor and that he had got a bit too
high before pushing over!

I explained to him that he was not to do "soft releases" behind my
towplane anymore, and we discussed the whole concept of safely
releasing from tow (turns out not all of our instructors teach
incorrect releases, fortunately), and then I went off to find a
certain instructor to have a discussion with.

And it's not just the new pilots who are clueless (either because they
have been taught wrong, or haven't taken the time to think carefully
about the dynamics of aero tow). Many of the experienced pilots
flying their own glass will pull up just prior to release, or soft
release (with a Tost!). Or aggressively turn away, as if they were
about to hit the towplane.

Just a little thought will show that 1. the towplane WILL accelerate
away after release (unless his engine just failed - which is a
different story on teaching aerotow emergencies), and 2. unless you
are being towed by an F-16, you are not going to get a lot of altitude
converting those extra 15 knots - better a careful look around than a
hard pull!

Doesn't say much for the level of airmanship being displayed....

Kirk
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