I had an incident today at the range that is concerning me. After ejecting my empty cartridges and reloading, I shut the cylinder...usually I spin it a little and it locks up. Today it just kept spinning. I pushed on it to make sure it was locked in place and it was. The thing is that this only happened one time out of about 30 reloads. Any idea what is causing this and if the revolver needs to go back to S&W?