Ive been using the moshi keyboard cover lately and always have been needing to clean it. The covers would go on the glass and imprint key marks on the screen... I know i can just keep my keyboard cover clean and wipe my screen but wouldn't this be bad in the long run? I mean, yeah the dirt/oil would wipe off but isnt the screen slowly 'deterioriating' the screen every imprint at a time? whether its visible or not?