i've had this exact same problem and i've been wondering the same thing. my guess is that you have too many pictures or album artworks on your ipod, so maybe you have to get rid of some.
I'm thinking about getting the LG env 2 and there's a deal with it that says you get one free. But 700 minutes minimum for a family plan every month is a bit much, so is there a way that I can use the 450 minutes for both the phones?