Yes, I left out that they still need balancing, but on the rear you won't notice an out-of-balance wheel that much. So I'd say to at least balance the ones going on the front. I do them all anyway.
I'm going to go out on a limb here and suggest that maybe you got ripped off on your original balancing, one way or another. Worst case, they didn't do it at all. Best case, the wheel weights came off because they didn't do it RIGHT.