2000 2wd Honda Passport Transmission?

Hello I have a 2000 honda passport, the problem is that occasional when I start the car there would be no light in the transmission indicator my car still drives but when I accelerate and stop, the car would judder. First time I noticed this is when I was driving and then I noticed my transmission indicator was on P. Restarting the car fixes the problem. Any thoughts on what is causing this? because I really want to find out the cause and have it fixed before anything serious happens to my transmission. Thanks