[Gameplay] Nasus's Armor and Magic resist keeps jumping around

I was playing Nasus and after respawning I couldn't help but notice that his armor and magic wouldn't stay the same and would keep switching very rapidly.

I am not sure if this bug is only applying to Nasus but if it's not Nasus's bug it might be because of the 9/21/0 masteries, more specifically the legendary guardian mastery that might have gotten bugged.

This is the match details: http://matchhistory.euw.leagueoflegends.com/en/#match-details/EUW1/2283894464/44293257?tab=builds&participant=8

And this is the video of the Nasus replay: http://youtu.be/qJcM9BlgsGM