The Misadventures of Sophie Juliet and her mother's not so smart moment

Today we went to Burgerville for lunch.  Nolan was at school so it was Sophie, Poy and I.  She likes to eat in the area by the bathrooms because they have a toy box there.  So, we sit down to eat and she immediately says "I gotta go potty". In my head I say "of coarse you do".  Anyway, Sophie has always been very independent when it comes to going to the bathroom in public.  Of coarse I would never let her go into a bathroom that I didn't have full supervision of who was coming or going, but it was a one person bathroom right by our table.  I opened the door and let her in and she locked the door.  She struggled a bit locking it, but she did it non the less. She was singing and having a grand old time in there and then it was time to get out.  She pulled on the door and I reminded her she needs to unlock it.  She tries... it doesn't work... she tries again... doesn't work.  Poy gets out of his chair and of coarse he says "I knew this was going to happen" "WHAT!!" if he knew it was going to happen, couldn't he have mentioned that?  Anyway, we attempt all kinds of things to open the door. At this point 3-4 Burgerville employees are trying to figure out how to help.  Sophie is crying and saying "I can't get out, I don't want to be here anymore"  All I can think is how I can get her not to panic.  She was upset, but I know her and if she went into panic mode, there would be no way to get her to do anything. She kept saying "Mommy, can you just help me? Mommy, can you unlock it?"  She had given up on the lock for a minute or so, then you could tell she was trying, but it was just a touch too high for her.  I had asked her if there was a stool, but there wasn't.  I asked her if she could stand on anything, but she couldn't figure out on her own what I meant.  Finally, I asked the employee if there was a garbage can she could stand on.  She said "yes, tell her to take the lid off the little garbage can."  I calmed her down and asked her to find the little garbage, take the lid off, flip it over and put it next to the door.  She did it and escaped without us having to break down the door.  This wasn't my finest moment... I felt pretty dumb.  So, I guess Sophie will not be going potty on her own until I know for sure that she can get out on her own.