Tim that is another good idea to try as a troubleshoot fix. I have not tried that. Eric also a good idea to try since it happened to you. Come to think of it, I believe that might certainly be the problem. Cant say for sure until I try it, but when I was testing, I think there was one time the light did come on quicker when I actually engaged the gear shift further forward. Must have something to do with the mechanism in the transmission that is activating the switch button. Just wonder if others have experienced the same.
Either way I will try both ideas and let everyone know the results. I realize this issue is not a major crisis with our Opel's, but something that is interesting to diagnose and correct or it could just be me