Well actually the support page where you type in your serial says that there is no need to take any steps if your serial number is affected but the button is fully functional. But as a matter of fact mine isn't, i just can't prove that to the "genius" since it is a intermittent issue.
Don't know what his problem was, probably annoyed by thousands of daily fanboys trying to get a replacement for non existent flaws on their phones
Probably will think about going to another store or trying it again there and ask for a manager