My baby babbles a lot! Is this normal? She's just 4 months old and can "talk" for a ten - 15 mins at a stretch, multiple times a day.

hehe..its definately normal. Infact it is a good sign=) When baby starts to babble..its when baby starts to communicate/talk in his/her own way. Do response and talk to your baby and engage him/her. You can read the link below. http://www.parents.com/baby/development/talking/when-do-babies-start-talking/