Sarah, is Lili's little sister in the midst of potty training right now? I know my 5 year old niece started having major "accidents" when her little sister was learning to potty train. The Ped thought it was because of all the attention and praise her little sister was getting for doing well in potty training and maybe she was trying to get a piece of the attention too. Good news is that it ended up being a short lived phase. Just a thought.