Leaf sets decrease

Anyone know why the number of blades on an outdoor 60/40 sativa would have random 3 bladed along with 5 bladed leafs? they were all 5.It is showing preflowers and appears very healthy. Thanks for any help!
( im hoping its just natural leaf blade reduction that goes along with the flowering process, just seams a bit early.) thanks!

Also they are approx. 4-5 ft tall.