its most likely just a stressed plant. When a plant is stress (for whatever reason) it will make 3 and 1 bladed leaves. Some times if the lighting period is interupting or if it reverts from flowering to veg it will do this. But it also could be genetic. Some indicas only have 3 and 5 prong leaves... but if its 6 foot tall then it isnt indica... i would say its stressed pretty bad... get some pictures..