Since your in soil I must suggest to flush this feeding then start in on the flower nutes.
My feeding schedule allows my plants to get just enough nitro till' about week 4. At week for I start to really push the phosphorus and potassium; however do stay at a low ppm/E.C till about 2 weeks...
Dunno it's happen twice on this same plant. I don't know what to anticipate in this sitch. The one thing that I will be watching for though is bud-rot. The flowers are going to be fighting for room so it will be an interesting battle non the less. I will definitely be updating that stalk often...
The reason for this is I like to grow bigger plants; the above in addition to the 36 hours of darkness helps to cut the stretch of outward growth. I've found that trimming after the stretch helps the grower to control what will & won't get light. Plus, I like to cut clones during this period...