Welcome to GenVibe! Glad to see you found the posts about the harsh downshift on the 2009-2010s and are heading to the dealer to hopefully get it taken care of. There was a TSB (Technical Service Bulletin) issued for it so they shouldn't give you any trouble.
Give us more info on your 2009 GT; color, any mods done to it, plans for future mods, etc. Also, post some pictures of it when you get a chance. We
love pictures around here

!