Can cheek fillers drop? 3 months post op. (photos)

I had cheek fillers three months ago and was ecstatic with the result until recently I've noticed that they have seemed to drop. Now the plumpish part is lower around my nose / mouth area making my marionette lines look worse. Where the filler was injected on my cheek bone doesn't seem plump at all and you can see on the photo there is a dent in my cheeks. Is this normal? Is there anything I can do?