New Tribunal system question, please help.

I took a break from the game for a couple of months, before leaving I had a series of warnings for bad behavior (Maybe final warning, don't remember) which was somewhat during August last year before patch 5.18 in September came out.

Before this patch 5.18 was announced a Riot employee stated on the board that accounts with any previous penalties will be wiped out and can start with a clean slate. Is this true? Is my account clean now? I have a clean slate?