Tresh buff ?!?

Dark Star Thresh just came out and i wanted to try him so i've made a custom , but something trouble me...

if i remember right his passive "Damnation" give 0.75 armor and AP for each soul, that's until he reaches 255 then he gain a buff called Glutonny saying that he has reach 255 souls and damnation go on again but ONLY give 0.5 per soul...

There is the problem ... in my game i reached 439 soul without activating glutonny.. soo that is 184 soul who gave me .75 instead of 0.5 (138 more armor and AP)... so has been secretly buff? or maybe it could be a simple bug ... what do you think

P.S. That build was so funny :D

P.P.S I am aware that i is not that relevant because you don't really go over 255 soul very often....