I installed the hardwood floor myself with the help of someone who has done this before. I agree that it is too soon to be seeing this kind of problem. The flooring is stripped planks with several layers. I forget the manufacturer, but I could look in the attic at the box (spares in case something like this would happen). The flooring is glued directly to the slab foundation. The floor is coming loose from the subfloor and causing a spongy feel as you walk across it. If you hop on the spot, the floor makes a popping noise as it seems that the floor is tacking to the glue and then releasing. Also there are two places where the planks are separating from one another. That starting about a month after installation and are at doorways.
I honestly feel that the spongy area is caused from water that was not cleaned immediately, but am not sure.
It’s an engineered or laminated wood floor that you have. You should have used a good adhesive like Dri-Tac 6200 which remains permanently tacky ALL its life. But you can use their Professional Wood Floor Repair Kit at http://www.dritac.com. Just follow directions that come with it.
Please read my floor maintenance article in the How To’s section, for better cleaning advice. But I’m sure it was the poor quality glue you may have used that is partly responsible for this problem. Manufacturers of laminated wood floor have been supplying an easy to use but poorly performing glue lately, so I always stick to my Dri-Tac. Some major hardwood firms have their warranties based on these poor adhesives, it a shame and a sham.