It's normal...same as the first time you were told that.Leaves will yellow as the plant uses the nutes and then it dies. to make room for light and buds.Later into flowering it happens more and more with some strains.As long as the leaves at the top of each branch and cola are still there...like 2-4 top leaves you'll be fine.Looks like Thai or some other kind of late frlowering sativa.