I do it alot. In fact when I went to order Ground Zeroes it was from another pre-order I was cancelling. I could tell the guy was aggravated with me and wouldn't make eye contact. My Gamestop used to be okay, but lately they always act like I'm inconveniencing them when I ask for something.
quick rant
I know they still have PS2 games put away somewhere because it shows on their stock checker. When I ask about a particular game they always just point to the shelf and say that's all they have. Really, buddy? Thanks, I wouldn't have thought to look there. I don't find what I'm looking for then I come back a few days later and there's more games on the shelf. You really couldn't just go look for me?