Unwanted In My Own Home?

I have had several experiences through out the years (which I hope to post here for feedback) but this one I think is the oddest one, and any feedback would be appreciated. This instance occurred a couple of months ago.

I live in a 2 bed apartment with me, my 14 year old daughter, my 4 your old son, and my 1 year old daughter (me and my husband our newly separated around a month or so). My mother came to visit and bring some sweets for the kids. She seemed to be in a hurry and called me out side to come grab them. I had my youngest daughter on my hip and my 14 year old daughter ran outside ahead of me to say hi to her gram. Now, My son was not at home at the time but visiting his aunt, and my daughter had one of her friends staying the night that night but she decided to stay in my daughters room and didn't come with us outside.

My daughter chatted with my mom for a bit and headed back in the house, I said my good bye's and was about 2 seconds behind her and when I tried to open the front door it was locked... I was a bit miffed and pounded on the door because I was directly behind my daughter and wondering why she would lock the door. She opened the door and immediately walked down the hall back in to her room and shut her door. I followed her in and tried to open her door to ask why she locked me out of the front door when she knew I was walking in directly behind her and her room door was locked! By this time I am more than miffed, she opens the door and has a weird look on her face and I asked her "Justice why did you lock the front door when you knew I was right behind you and now your locking your room door!"... She swears she didn't lock either door and her friend that was staying the night was able to confirm that she did not lock the room door. (she had stayed in the house in my daughters room while justice ran outside to chat with her grandma).

Now the doors in my apartment are the little twist locks where you turn the little tab thingy in the middle of the door knob and the front door has a dead bolt... Neither of these just lock on their own or could possibly be half turned because when you turn the knobs when their half turned it will just pop it back to the unlocked position. So I am really confused. I just kind of felt a little unwanted in my own home lol or that someone was playing a trick on me. Not sure what to think... But any thoughts would be appreciated.