Unless you have frost built up on the back wall of your freezer you'll still have a sealed system problem. If it's a leak that took went 4 months without notice it's unlikely your servicer will find it. The only thing to do is ask them to replace the filter w/ one that has a dye pack. Than they can drop by in a week or two see if any dye is coming out of joints. I would be sure to use an authorized servicer and ask him to call tech line to document the problem and ask for an exchange. Exchange is not likely but always worth a try. If you started having problems under warranty you have a shot.