Death Cap bug
The bug happens in normals (randomly:1/5 games) and secondary game modes (ever time) i noticed it start happening after the 5.6 patch. Reasoning as to why it may have some thing to do with the patch last night i played the same game modes and no bug had happened. bug also effects nashor's tooth passive scaling.
Added: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1771982961/211184069?tab=overview (march 25/2015 1:32 pm)