Nasus bugs? or intended game mechanics?

There have been 2 bugs which I have encountered a lot while playing Nasus:

1. Sometimes when I use Siphoning Strike and go to auto attack a minion, it will die an instant before my attack hits it. This will cause the Siphoning Strike charge to be consumed, and if i have Sheen the Spell-blade effect will not be consumed (I thought Riot recently fixed this in a patch for a couple of champions).

2. While using Fury of the Sands, Nasus has increased size and attack range. If I am mid auto attack while Siphoning Strike is active, and my ult ends, the auto attack will be canceled. I think that because he is already mid auto attack, the attack should be completed.

What are your thoughts on this? Do you think these are bugs or are intended game mechanics?