Sounds like you got them to do what you wanted, which is good.

I've encountered this sort of thing many times-- say Circuit City
a local retailer of electronics.  They have a X day return policy.
During the X days, the price dropped on something I bought.
I asked them to give me the difference. Initialy the person I spoke
with said "no."  I simply told them
I'll bring the thing back, return it under the X day policy, and
buy it again at the lower rate.  After I mentioned this, they
refunded the difference and I didn't have to bring anything
back.

The same goes for your 15 day policy. You have the option
to cancel if they don't take care of you.  After the 15 days
you really have no leverage whatsoever...  This is not to say
that Verizon isn't good to folks in contract, but their policy
after 15 days will be to give you  a refurb...

Incidentally, my Kyocera 7135 started having problems last
week (bad microphone) and they exchanged my phone for
me with very little hassle (and I am in-contract).  The replacement
in my case was brand new (well the all-calls timer was 10 minutes
which I presume is quality assurance testing etc.)

Anyway, for basic things I really need, I've found Verizon has
done a very good job.   Most of the people I see who are very
unhappy don't understand common cellular practices with any
carrier, and by that measure, may have unrealistic expectations.
By the way, I thought you handled this perfectly.

-Dan