I'm thinking autocross results in more possibilities for this to happen to you. It could have something to do with the ECU adaptive learning. The harder I drive the more my car holds a gear. Or the fact that I usually maintain some throttle in the corners. I'm giving my car some gas before the apex. I always downshift manually and let the car upshift. Or maybe I've adapted my driving and know the tracks to the point that I don't let it happen. Whichever scenario doesn't help you much.

Les