At the moment your finger passes through that point midway through the key where the hammer contacts the string (the little "bump" or whatever in the key, when the sound begins) - what direction is your fingertip traveling as it passes through this point? Towards your body? A little to the side? Maybe pushing a little bit way from your body towards the back of the piano? Straight down? Maybe you try and hook this spot with your finger? Interested to see what people observe in their playing.
Topic: Vectors through the keys