I have a question about this, maybe you can help. I did an early Edge upgrade, too, but nowhere in my order process or email confirmation has there been anything about the phone return. Did you see anything during your process?
You have to return the phone or else Verizon will bill you for it. It'll be on your next bill. Just make sure you return the phone within 14 days of when you get your new phone activated and you'll be ok.