I'm not so certain that the issue is the definition of the term normal, so much as it is the value (positive or negative) or association (healthy vs. unhealthy) the term implies in a medical or social context.
One of the most common reasons for blurry vision while wearing contacts is that your eyes are dry. Some people have a medical condition that causes dry eyes, called dry eye syndrome, but others' eyes are irritated by the contacts themselves.
Blurry vision is often one of the first warning signs of diabetes. Your vision may be blurry because fluid is leaking into the lens of your eye. This makes the lens swell and change shape. Those changes make it hard for your eyes to focus, so things start to look fuzzy.