Track bars - an odd reaction??

I thpught the OP described an iteresting phenomenon, I think it may be that the shape / design of the bars encourages that particular movement, rather than, or as well as any anything subconscious.

It has happened to me riding brakeless on the road, but disappears the moment I'm on the track.

I've observed an opposite fenomen, mainly amongst people who started with a "fixie" and then moved onto the road bike. They'd often ride in a sit and beg position instinctively searching for a short brake lever in the close vicinity of the stem.
I'm sure you've seen people who had a secondary flat bars type lever (or BMX one) fitted on the top of drops.