My 6-month-old babe can now mimmic her auntie’s hand gesture (while dancing and matched with music)! Such a delight! Is she considered a fast-learner or typical at her age? :)

That's so cute! Have you taken a video of it? It's a nice memory to capture. According to Parents.com, the developmental milestone for mimicking actions is from 8 to 12 months old, so I would believe that your baby is a fast learner. Your baby will also imitate other actions, including undesirable actions so do be careful of her surroundings. http://www.parents.com/baby/development/growth/8-12-month-milestones/#page=15