Parakeet making "Fighting Noise" when not fighting?

One of my four parakeets aka budgies, keeps making that little fighting noise like when they get into a little scuffle or argument among eachother, that type of whiny, complain noise they make (lol hard to describe, if you have a parakeet you would know what I'm trying to say)....... thing is he isn't even fighting sometimes he just does that noise out of nowhere, is something wrong with him or is that normal?