[Gameplay] Hextech Skin Rental

So i got this Dunkmaster Darius as a Shard and was really happy about it and was saving it for the shards. Then the next day, the shard was gone! I was wondering what happened but it automatically did the "rental" action by itself and consumed the shard itself. Is this supposed to happen? Now i only have 5 days of this skin left where i wanted to upgrade it to permanent lol

Please any advice would be appreciated. Thanks