Does this happen when the window is down or up?
My 280ZX does this also, but mainly when the windows are down or even halfway down. What I have done is move the door catch back about a centimeter or two and tighten it down as much as I can. This solves the problem for a while but eventually returns. Another possible solution is to mount something on the door that pushes the door switch further so when you go around curves the light won't come on. Just a thought.

VernonZ

 

Sounds like car is flexing, you might want to get strut tower braces if your gonna push your car that hard.

 

your door might just need adjustment... over the years it might of got out of alignment..

 

Ya, I remember my car doing that too. I adjusted the door stopper in as was suggested and it has been fine for over 6 years. If the rubber cover on the door light switch is worn off, then that lets the switch stick out that much further. Replace the rubber cover or put a small spacer plate on the door.