Asphalt settlement at the garage is a very common problem and usually has nothing to do with an insufficient base. The settlement is usually due to an unavoidable side effect of new construction. Many new homeowners have a hard time accepting this, but it's possible for a properly installed driveway to settle in the first year. When your house was built, they started by digging for the foundation; the Builder has to dig a few feet further than the foundation, this is called the over-dig. Once the foundation is done, the over-dig area is backfilled. If the backfilled area were allowed to settle for a year, we wouldn't see this type of settlement. Builders are forced to install the gravel base and pave in short order (to get occupancy permits), while the sub-base slowly starts its natural settlement - bringing the gravel and asphalt with it. As time goes by, the sunken area collects water, accelerating the settlement.
In some cases the settlement can be due to undermining, holes may accompany the sinking. If this is happening, look at the edges for clues to see if a rodent is tunneling under the asphalt or if water from a downspout is washing away the gravel base.
If the rest of your driveway is in good condition, then an infrared repair is a good solution to either of these problems. The infrared repair will bring the asphalt back up to the right grade and provide a thermally bonded repair. However, if you have multiple problems, it may be more cost effective to repave.