94 Grand Prix GTP Ignition key stuck
 

1994 Grand Prix GTP. Sometimes when I turn the ignition off the key does not turn all the back so I can not remove the key from the ignition. Goes back far enough to turn off the engine just not all the way. Not sure if it is the ignition cylinder, maybe the shift park swith or what. Also, it seems that if I leave it alone for about an hour and let it cool ff then it works. Any ideas?
Thanks.