Why can I play akali when I don't have her.

Okay, so after banning a champion I notice was a available. I thought was in the free rotation, because I don't own, but didn't see the little mark that said she was in the free rotation, I assumed it was a client glitch and went with it. After that game I checked my collection said I don't have her, checked the store said I didn't have her, then checked the rotation table and she wasn't in the current rotation. I don't know what I did or how this happened but at the moment I am able to play as . I'm posting this in the forums because I don't know if this is a glitch that will go away once I long off or if it will allow me to play as her permanently. Also if anyone has experienced this as well.