Our cocker also had several fatty cysts, one of which was several inches in diameter and on her side. Another one was on her leg, and entwined itself and adhered to the bane and tendons - that one gave us a scare because it didn't move like the others. The vet removed the one on her leg and biopsied it, with the results being that it was just fat.
Talk to your vet - since it's loose, it probably is just a fat pad, but better safe than sorry!