Greater Vision Trinket Skin Bug

While playing with my new grim reaper Karthus skin (thanks Riot!), I noticed a strange bug after upgrading my warding trinket, which was working like normal, to the greater vision totem trinket. Instead of a normal pink ward, it had the spider skin from the harrowing 2013. Since I didn't buy that ward skin, I was surprised that there was a spider. When I placed normal pink wards (not from the trinket) they looked as I expected, with no spider. This was very peculiar, so I told everyone about it in /all chat, and everyone tried it out with similar result. I went into custom games was able to replicate the bug, but only when I used a skin (I own phantom Karthus, reaper Karthus, and butcher Urgot). Different ward skins appeared for each skin I used, consistent across games for each skin. Whenever i used a champion with no skin, even Karthus who I knew caused the bug with a skin, and the bug never occurred.

TL;DR: Using the pink ward trinket makes the ward to have a skin if your champion has a skin