Why Should Filler Lumps Be Massaged Out?

I had perlane a week ago on my nasolabial lines and was concerned about formation of lumps. They were not seen but critically felt after the injection. So, according to some replies received to my previous query, these lumps should be massaged out. They are normal after a week or two, most doctors said (even though one of you said "not really normal"). However, after initial swelling, no bruises, it looks really beautiful,despite some lumpiness still there. Why should I massage them out?