When? I'm honestly having trouble remembering that happening. Maybe anakin force pushed mace, but that wouldn't really count because Mace thought Anakin was his ally. Did Dooku force push obi wan in the beginning of episode 3? Perhaps it happened a lot in comics, I never read those.Except they fail to defend against force pushes all the time,
But I recall at least one book that dealt with early training, and they talked about how one of the first things you learned was how to not get force pushed all over the place.