I'm almost certain that zhonya's hourglass' timing is a little off.

I could of sworn last patch I was playing , and I threw one of Nidalee's spears at somebody with Zhonya's Hourglass activated. Something strange happened upon impact. It appeared my spear was timed perfectly so that it still made impact with the person, but didn't do any damage as if Zhonya's Hourglass was still active.