Yes it is protein, but not really to do with your method by the looks of it.
In order to reduce haze a beer must be chilled to below the ideal serving temperature and held there for several days. A cask beer for example would ideally be chilled to 6-8C and then served around 12-14C thus eliminating the haze. Lagers should be chilled to as near freezing as possible as obviously they are served colder around 6-7C.
Without knowing what your kit can do, this is my best guess.
Can't be arsed to keep changing this bit, so, drinking some beer and wanting to brew many more!
Sir, you are drunk! Yes madam, and you are ugly, but in the morning I shall be sober! - WSC