gender confusion

My 4 1/2 year old boy is drawn to female characters more so than male characters in his movies and character toys. For example, if he watches Disney's Tarzan movie, he pretends he's "Jane" for days rather than "Tarzan", etc. He also seems to choose girls to play with rather than boys.

This has been pretty consistent behavior for the past 2 years or so. Is this something we should be concerned about or something somewhat common that he will grow out of?