I have had my clear retainer since May 2011. I wear it at least 22 hours a day as instructed, but have something that indicates my teeth may have moved. When I first got the retainer it formed perfectly over my teeth (obviously). Now when I look closely in the mirror I have noticed that not all my teeth go to the bottom of the retainer indicating that it doesn't fit as properly as it once did. Are my teeth moving or is the plastic wearing out? Also, will playing a brass instrument with this retainer on have any ill affects? (Maybe that's causing something to go wrong)