Is it O.K to lock the door?

Not that long ago I wrote about the magic words that made going to sleep a little less traumatic. While they have not completely lost their magic power a little person who shall remain nameless decided to test her boundaries a little bit. We did the routine the same way, I would lean in and whisper I love you Bobo I'll be back in an hour and the words prevented crying and arguing and trying to scramble back out of the bed. But there was a BIG but and that is she would con me in to thinking she was going to settle down and then as I ate my lunch downstairs I would hear little noises. I would mute the t.v and listen, nothing silence so the volume goes back on and then another little shuffling or thud. Hit mute, again nothing. Another noise no, the denial took over I did not actually want to go check that would lead to a confrontation, a tantrum, tears, guilt. So I just ignore the noises then I hear a little tiny giggle and it sounds very close. I mute the t.v again and look in the kitchen and I can see a little shadow peeking out from the side of the refridgerator. As I close in on the "shadow" the giggles increase. Then the escape artist was cornered her number was up. She thought it was fabulous. I thought oh great I have to break out the baby gates again and I hate those things they are a pain in the you know what. So here is the brilliant plan I hatched I will shut her bedroom door. Are you all impressed or what? You know I just never shut the door all the way because I assumed that would scare her because her sister has to sleep with the door all the way open ( which until she was 3 the doors had to be shut all the way or she would calls us back upstairs to properly shut it) and they are exactly the same right? I am always falling in to the trap of thinking they both see things the same way I always overlook the vast differences in their personalities. So I marched her back upstairs and put her to bed and shut the door. As I made my way downstairs I could hear her little flat feet pad to the door and then she shook the knob and twisted it but much to my surprise there were no tears. As an adult I would be horrified to realize I was in a room with no way out. Apparently Bobo did not see it this way she worked on the knob for about 15 minutes and then it was quiet. When I checked on her an hour later she was in bed sound asleep with her covers perfectly pulled up to her chin. When she woke up I asked her how her nap was and she said "mama you locked my door so I went to bed". So that has been the solution at nap time and for some reason at night even if her door is wide open she won't leave her room. In fact when she woke up yesterday morning she called downstairs to me "mama, mama, is my door locked" and when I looked up the stairs she was standing in the open door asking me if it was locked. So no need to worry I don't really lock my kids in their room they just think I do.