My Sister In Law Has Alzheimer's, In Or Getting Near

My Sister in law has Alzheimer's, in or getting near late stage. Very recently she has started a new behavior that is worrying my brother- her caregiver- she apparently will stop in the middle of doing something and seem to freeze in place- and stay that way for several minutes. Like bending down to do a simple task and suddenly stopping- still bent over- like a robot that just ran out of battery- is this a symptom of the disease?