2001 XC70 vents blowing

Hi all, first post here. I have a question about an issue that has come up. I just purchased a 2001 XC70 last week. 89000 miles on it.

Last night and now again tonight after coming home and putting it in the garage, once the electric cooling fan stops, it starts to blow from the interior vents !! No key, nothing on, car locked. Is this normal, is there an issue? It is my wifes car and I am afraid she will get stranded at work or someplace else with the fan running and a dead battery. PLEASE HELP

Thanks
-Darin