[crena]

This. I feel like this is due to small shifts when lifting the finger. For the life of me, I cannot get myself to lift it like the testers at Apple do, and so I wished the product itself could go through learning phase; studying intentions and what actual touches happen.

[Pulcinella]

Apple devs are probably doing something with the touch returned by the touchUpInside callback. This is an extremely, extremely common bug in iOS apps, not just with Apple developed software.

Devs love the symmetry of their touch handling code and often have the finger-down, finger-moved, and finger-up callbacks from the system all call the same handleTouch function they wrote. As you can tell, however, the touch from the finger up callback is often better discarded or handled differently otherwise you get these sort of bugs