Craving Peanut Butter!?!

I don't know how normal or abnormal it is, but lately all I crave is peanut butter. Does anyone else get this? I was told by a friend that if I crave peanut butter during PMS that means my body needs protein, again I don't know how true or untrue that statement is... I just want to know why I crave peanut butter more so during PMS than I do any other time.