The Cure's 'Boys Don't Cry'

My 2 1/2 year old daughter, Sophia, hummed to the opening guitar riffs of The Cure's "Boy's Don't Cry" today. I was playing the song on my mobile phone when she started to take interest to the song. That was also the first time I heard her hummed the melody of any song. She normally sings part of the verses of songs she liked but never hummed to any before this.