My drive is only so many years old, can it be defective already?

Age is not a very reliable indicator to predict when a drive might fail.

These high-tech devices operate at rates of 4,200 to 10,000 RPM (rotations per minute), and can fail within the first couple of weeks, or last in excess of 6 years.

They WILL fail eventually though, which is why it's important to have a functioning backup system.