Prius key at shut down...

hi guys i recently have a problem with my 2002 prius, when i shut down the car the key gets like blocked and it doesnt comes out, i figures out a way to get it out i have to unplug the battery and then the key comes out what could this be?? it happened since wednesay and i though it weird but i think if dont get it fixed it will be happening like...4ever hahaha, so any help would be appreciated it thanks!