Warning about Apple Nano! December 15, 2007

I purchased a Nano for my wife today as a present.  My wife and I share our e-mail and as an aside I think it is weird for married couples to have separate e-mail accounts and bank accounts etc.  Well I check my e-mail and Apple has sent me an e-mail receipt for the Nano which my wife would have seen if she had checked our e-mail first.  The strange thing is I never gave the sales people my e-mail so how did they have it.  Why do I need an e-mail receipt when I have a paper one from the store?  Has any one at Apple ever found out that these e-mails can blow the surprise that their customers were hoping for?