smoke24answered grow question 4 years ago 72% is quite high for this stage of growth, 60% would be much better. Those spots on older leaves are quite common. Things to check aside from adjusting humidity would be runoff ph......remember in coco you want to be at a lower ph than if you were growing in soil, I try and keep my ph around 5.9 plus or minus .2
But the plant looks good, and if the problem doesn't worsen after you've made some adjustments you can pinpoint what the problem was (adjust one thing at a time, making note of if the plant responds positively or not). Happy growing.