Hi AmyPink,
It would be very unusual for any high quality mattress (latex or otherwise) to be sagging after such a short time unless it is one of the very small percentage of cases where there is some kind of defect in the materials. How deep are the impressions in your mattress? Have you measured them?
It’s also possible that the impressions you are referring to could be coming from your wool topper which would be normal when you first sleep on a wool topper (see post #3 here).
If your mattress has developed visible impressions after this short a period of time then I would definitely talk with Sleep Nation about whether it may be defective.
Phoenix