why doesn't glue stick to the inside of the bottle?
That is a qustion that I don't even think common science can solve. I think that they put some kinda laxitive on the inside surface because when manufacturing began, they ran into that prob.
Well, the actual glue doesn't fit inside of the bottle. It stands on an object that holds in in place. Sometimes the object gets loose and can't hold anymore, therefore making it fall out.