Hey, now singed onto Tuner after a while...noticed this post. I'm not sure if you got it fixed already...
Yes, this is a common fault with that model on one of the rear door locks. I'm assuming your technician disabled the push button for that specific door so the light won't come on/off, however I believe the lock needs to be replaced. Also occurs on Mazda 6 (same gen). I have both and fixed them that way.
You can order the part on ebay...unless you get it here from MazTune or other f/used parts place. Replacement is a bit of a task unless you're experienced with it...but should take you 30-45 mins depending on your skill level...(15 mins second time around