Headlight warning driver side u/s

OK, my car very unhelpfully notifies me that I've left my headlights on if I happen to open the PASSENGER door, but neglects to let me know when I depart the driver's side of the car... GAH. Anyone have this problem and know where to find the fix? I now have a parts car if I need to shop for a new switch...
Thanks for any help!

2003 Mazda Protege5

Does the cluster show the driver door is open when it is closed? That would indicate the sensor has failed. It's a simple plunger switch, you can swap one from another door if it has failed, or you can inspect it the switch for corrosion.

Door switch is not working, it doesn't know that your drivers door is open.

I stand corrected! I just confirmed the door open was not actually indicating (thanks @MrGiggles). I pulled the switch out from the door, and not only was the plunger part semi seized, the tiny little wire was broken off at the back of the connector. I decided it wasn't worth the hassle to figure out how far the body harness would need to be removed in order to replace it so I opted to splice the "new" switch into my harness. I'll do that when the rain stops - my parts car is in a portable garage but my regular rig is outside...

The good news is I am able to replace both front seats with factory leather replacements from the parts car (the main reason I bought the second car). I already did the passenger side and will do the driver side when I go in behind the seatbelt assembly to splice in my new door sensor.