Did you go in and try to resettle when she woke early for the DF?
Some babies do start to wake for it, some always wake. It could be developmental, it could be that it's disturbing her sleep now which is why it's weaned around 7/8 months.
If she settles straight after the feed I wouldn't worry too much really or it could be a sign that you need to start to wean it now.
Laura