random mutation. happens.
Progressively as a plant matures through its vegetative state, it will gain blades on it's leaves. Indica usually tap out around 5-7 blades per fan leaf when they go deep into veg. Sativa on the other hand reach as high as 13 blades per fan leaf. Then you will notice as you turn that plant into flower, the deeper the plants go into flower the less blades per leaf they have. Both sativa and indica will have 1 blade per fan leaf on new growth once they are deep into flowering.
But for your first shoot to throw out three blades like that is crazy. Maybe the top got damaged and it did that to recover. But likely just a harmless genetic mutation. I used to have a strain with this crazy thumb leaf mutation. The first set of leaves would ALWAYS be a set of paired blades that resembled a nike check. One blade clearly dominating the other smaller blade. Was only from seeds from one particular breeder, so i'm sure it wasn't a coincidence.