Koji just found the emergency exit door unlocked again. NOT GOOD.
We have determined that if you use the emergency door to enter the lab, it leaves the door unlocked, unless you go back outside and deliberately lock it. This means that someone has been using the emergency exit as a regular entrance.
It's fine to leave by that door, but you should make a habit of entering through the regular door. Using the back door as an entrance is a special case situation, when they have the main door blocked.