My daughter once mounted her barney doll at age 3,so I think anything like this is pretty normal,LOL.
Yes it's normal. I'm a girl and I experienced w/some crazy things too. It's a child's way of discovering and exploring their feelings, genitals, and pretty much their sexuality. It's not weird at all.
and an answer to this would help you how?
This really is a very common behavior. Most young boys first learn how to masturbate by contact with some kind of friction- and a mattress or bed post is quite common. "Normal" really is a tricky word- because we don't really know what average behavior is,much less what would make that normal or abnormal. In general, those of us who study sexuality consider something abnormal if it is abusive , not mutual or wanted behavior, if it imposes guilt or shame or if it undermines ever being able to have a sexual relationship with another human being . Please don't be concerned about your behavior- it is very common , not at all dangerous in any way, and almost unavoidable!