How come 3G still shows on my iphone 4 but it is no longer in service?

I had an iphone 4 but then i got a new iphone 5. Verizon switched the phone number, the cellular service, and the data plan (3g upgraded to LTE for iphone 5) to my new phone. The iphone 4 should be out of commision, that is, unable to use for cellular service, or any internet (other than wi-fi). I want to sell the iphone 4 but when I turn it on, and it goes to the set up wizard because it has been restored, it still shows 3G in the top left corner. Does this mean that the 3G has not been disabled from that phone by verizon? I'm worried that if i sell the phone, someone will be using data that will then be charged to me.

Also, if i did a restore on my iphone 4 and restored it to factory settings, that means that my mail accounts, contacts, etcetera are all gone and unable to be viewed once set up again on the iphone 4, correct?

Do you have sprint.