In regard to the thread's title, "does the iPhone's warranty transfer?", I could not find anything regarding "transfers" via Apple Warranty page, but I did find the following via a different site:
"Other retailers stick with Apple's standard iPhone warranty, and this warranty is transferable if necessary. If you sell your phone, you can increase the resale value by selling within the warranty's one-year coverage time, or within the AppleCare+ coverage time. The remainder of the warranty can be switched to whoever bought the phone." Source: Things to Consider About the iPhone Standard Warranty - Apple.Answers.com
Whether the above is true, I cannot say. Anyway, feel free to read Apple's warranty page via the following link.