Riot, I have Sweetheart Annie, but I didn't purchase it?

I saw the Valentine's day stuff came out and went to the store because I wanted to buy her skin. I couldn't find it so I went to the champions page to see if I could buy it from there but it said that I already owned it... I went and looked at my purchase history and it is in fact not there at all.

It's cool and all but my biggest worry is that if this skin is only out for limited time, then it phases out but is also taken away from me, I will have missed on being able to actually purchasing it. I already own every purchasable skin so getting it through mystery gifts is not an option.

Help?