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.
If the growth gets onto your cornea (the pupil area of your eye), it could change its shape and cause blurry vision. Before it appears, you might notice a related condition called a pinguecula (pin-GWEK-yoo-la). This is a yellowish patch or bump on the conjunctiva and can get red if irritated.