Aram Skin Boost Bug

So my friends and I were playing Aram we were a full team. Then one of my friends decided to use the skin boost while i was playing Mordekaiser and I had my mouse over the picture of the skin I was gonna use even though i didn't have it and then the next day i play mordekaiser and I have PentaKill Mordekaiser still unlocked and now its permentley unlocked for me also I know I didn't accidentaley buy it because I have 0 rp