happened to me with a 73 Torino years ago.. parked it on an incline and put in park... came our of store and could not get it out of park..had to get someone to get behind me with their truck and push it about 2 inches so the paul i the transmission will release from the park position..... this might be your problem if on an incline(ever so slight) the weight of the car is pulling on the paul(the thing in the transmission that stops the car from rolling when in park).....solution for me was that anytime i go into park i put on the E-brakes before releasing my foot off the brakes so the car does not roll back and lock onto the paul.. it can happen with late model cars also, the paul never changed in years...its doing its job.....
