Questions about returning iP4

[deimos256]

So I had a 3g and upgraded to a 4, thus signing a new 2 year plan, now since I am within my 30 day window, I should be able to return the phone and nullify my new 2 year contract. When I called apple they agreed but said to check with AT&T, so I call them and the lady didnt sound like my new contract would be cancelled. I realize you cant really believe anything that comes out of a CSR's mouth. But has anyone here returned their 4 that they got on an upgrade and had their new contract wiped out as well?? Thanks for the help.