My 13 Year Old Daughter Drove Us Crazy Masturbating From

My 13 year old daughter drove us crazy masturbating from the time she was 8 or nine now at almost 13 she has just quit. She says she hasn't done that in months she did start her period is it possible that her hormones are acting up ? Seems strange that after years of non stop all the time now she just stops, is this normal ? Thank you