question about return/re-purchase

so i had noticed a problem in the last week or so with part of my screen being not very responsive. since my 30-day period was almost up, i decided to go exchange the phone.

i guess i didn't realize that the exchanged phone wouldn't have a 30-day period of its own. i didn't want to have just two or three days with the new phone to find problems so i just cancelled the purchase.

i figure i can just go to another shop tomorrow to get a new one (hopefully i'll survive the night without a droid :). does anyone know whether i'd have any problems doing this? the customer rep cancelled my data plan but i'm sure they should be able to add it back in, right?