Why is my 19 month old so suddenly attached to her blanket?

She gave up her pacifier with no problem at about 6 months. She just didn't want it anymore. She has a favorite blanket since very young and would take it or leave it but did have a certain love for it. For the past week she cannot be without it. She will take it everywhere, drag it on the ground behind her, hold it in her high chair while she eats, keeps it in one arm while she plays. We cannot leave the house without it because she will scream and cry. She has always just slept with it and that was it but now, her relationship with it has totally changed. We can't leave without it. It doesn't bother me, I am just wondering why all of the sudden she is doing this. This is the same blanket she has always had and there have been no sudden changes in the family environment.