2001 Infiniti I35 Getting out of Park

WHY?
All of a sudden my 2001 I30T is hard to get out of park. The button on the shift handle only goes in part way---UNTIL--I push harder on the brake pedal or just keep pushiing and wiggling the shift handle until---it goes in and then to R or D. I have not figured the exact sequence when it does work. Most time on a hot start it works just fine. No forcing is done. The car has not been in an accident.