Justified suspicion

One of the libraries in my new system has some high-tech locks on the study rooms. You hold your palm up to them to 'wake them up,' then enter a code to unlock the door. Holding up your palm to the lock again locks the door. I was showing this to a patron when I was on the desk this evening in case she wanted to go out to the bathroom without having to take her backpack with her. When I opened the door for her with a flourish, she looked at me hesitantly.so I said "Do you have a question?" She said "So...that lock recognizes hands?" "Oh!" I said, "No, it's not that high-tech. It doesn't know that it's your hand or my hand, it just knows that there's a hand in front of it." The patron sighed and said, "Okay, good. I wasn't sure I wanted to go into a room that was smarter than I am."